Lesnar has suffered a recurrence of diverticulits. This same illness caused Lesnar to be out of action, for over a year following his bout against Frank Mir at UFC 100.
While everyone in the MMA community wishes Lesnar a speedy recovery, he is the latest to be added to the list of athletes who have suffered injuries and illnesses that have shortened or ended their careers.
Although there are way too many to list here, I present to you 15 athletes whose careers were unfortunately short changed due to circumstances beyond their control.
When Lesnar first announced he was going to give the sport of mixed martial arts a try, many didn't believe he would be more than a sideshow attraction.
Brock proved them all wrong very quickly.
After only one professional fight, he was signed by the UFC. After losing his first bout to Frank Mir, he rebounded by defeating Heath Herring.
In his next match, he went up against Randy Couture in a match to determine who would fight for the undisputed UFC heavyweight championship.
While Couture held his own, Brock's size finally wore down the much older—and smaller—Couture en route of earning a second-round TKO victory.
Then at UFC 100, Lesnar took on Frank Mir once again. This time around, Brock was able to control Mir and scored a second round TKO victory to become the undisputed UFC champion in only his 5th professional fight.
After taking a year off after his first bout of diverticulits, Lesnar returned to defeat Shane Carwin. In the next defense of his title, he lost via TKO to the undefeated Cain Velasquez.
Now dealing with a second case of diverticulits, one has to wonder if we'll ever see Lesnar in the Octagon again.
For years, Griffey Jr. was not only among the best players in baseball, but he was also one of the most popular.
To this day, pulling his 1989 Upper Deck rookie card out of the pack is one of my most fond childhood memories.
While he will undoubtedly be inducted in to the MLB Hall of Fame, injuries towards the latter part of his career turned what could have been one of the greatest careers in baseball history in to a great career.
In 2002, injuries caused him to miss the better part of the season. While he did have a few productive seasons before his retirement from baseball in 2010, his constant string of injuries prevented him from achieving numbers that only a few elite have reached in their career.
One could only wonder what his career numbers would have looked like had he not been so injury prone.
Petrovic's NBA career got off to a slow start, but everything changed once he signed with the New Jersey Nets.
Petrovic was given the playing time he wanted, and ran with it. He became one of the best shooting guards in the game, and also became one of the most popular basketball players in the world.
On June 7, 1993, Petrovic was taken from this planet far too early when he was involved in a car accident while traveling in Germany.
In 2002, Petrovic was inducted in to the Naismith Memorial Basketball Hall of Fame.
After a failed stint on the Ultimate Fighter reality show, Hill was given an opportunity to fight in the UFC. In his third bout with the promotion, he suffered the worst injury in the UFC's history.
During his fight against Dale Hartt in December 2008, Hill threw a kick to Hartt's lead leg during the opening moments of the second round. Hartt checked the kick, and shattered Hill's right leg in the process.
This injury kept Hill out of action for more than two years. Since his return in 2010, Hill has gone 2-2, and has not fought in eight months.
After a not-so-successful comeback after a horrific injury, one has to wonder if Hill will continue his MMA career.
It doesn't matter if professional wrestling is fake, it takes a great deal of athleticism to do what they do night in and night out.
Andre the Giant, born André René Roussimoff, was one of the greatest attractions in professional wrestling history. His feud with Hulk Hogan in the 1980's was one of the greatest in sports entrainment history.
Roussimoff was born with acromegaly, a disease which caused him to grow at an abnormal rate. By the time he was 12, Andre was 6' 3" and weighed 200 pounds.
On January 27, 1993, Roussimoff passed away in his sleep due to heart failure due to his life-long illness.
Upon his arrival in the UFC in 2001, Mir was hailed the next big thing in the heavyweight division.
After going 4-1 in his first five fights in the promotion, he was given a title shot against then belt holder Tim Sylvia. It took Mir only 50 seconds to snap Sylvia's arm in half and win the UFC strap.
After that fight, Mir was involved in a motorcycle accident which severely injured his leg in knee.
When he made his return to the Octagon 20 months later, he suffered a TKO loss to the lightly regarded Marcio Cruz.
Since that bout, Mir has gone 6-3. He has had some great moments since his return, but his short-comings outweigh his highlights.
Theismann was one of the best, if not the best, quarterbacks during the 1970s and 1980s.
During his run with the Washington Redskins, he led them to two Super Bowl appearances, won Super Bowl XVII, and set Redskins career records in career passing completions and yards.
Then during a Monday Night Football game against the New York Giants, Theismann was sacked by Lawrence Taylor and Harry Carson.
"The Hit That No One Who Saw It Can Ever Forget" left Theismann with a compound fracture of his right leg.
During his rehab, the shattered tibia suffered from insufficient bone growth. That led to Theismann's right leg being shorter than his left, and ended his football career.
Diaz was a hot, up-and-coming, prospect in boxing's welterweight division. On July 16, 2008, he squared off against fellow prospect Delvin Rodriguez on ESPN's Friday Night Fights.
While the match was very competitive, Diaz started acting abnormally towards the later rounds of the bout. Then after the 11th round, Diaz went back to his corner, yelled out something, and collapsed.
Diaz was rushed to the hospital, where it was discovered that he has suffered a subdural hematoma.
After emergency surgery, Diaz was in a coma for two months. Seven months later, he released and moved to a rehabilitation facility.
Needless to say, he will never box again. But hopefully, he will recover and be able to lead a normal, healthy life.
"Baby" Joe Mesi had everything it took to be the best American heavyweight boxer since Evander Holyfield.
During his 2004 bout against Vassiliy Jirov, Mesi may have won the fight, but it came at a terrible cost. It was revealed, after the fight that Mesi had suffered at least two subdural hematomas.
Even though many medical experts believe that a fighter should no longer be able to fight after suffering a brain bleed, Mesi was somehow cleared to fight again in 2006.
Between 2006-2007, Mesi fought seven times, running his record to a perfect 36-0.
Thankfully, he left the sport for good in 2007. Should he not have suffered the injuries in the Jirov fight, Mesi might have became one of the best heavyweight boxers of Generation Y.
Thurman Munson was considered the heart-and-soul of the New York Yankees.
During his 10-year career, he became the first captain of the Yankees since the great Lou Gehrig.
Also during his career, he led the Yankees to two World Series victories, made seven All-Star teams, was the 1970 AL Rookie of the Year, and was the 1976 AL MVP.
The tragic end of his life came on August 2, 1979, when he was practicing landing his small aircraft. He was only 36 years old.
"Our captain and leader has not left us, today, tomorrow, this year, next ... Our endeavors will reflect our love and admiration for him."
Ming made a huge splash in the NBA upon his arrival to the Houston Rockets in 2002. At 7'6", he is the second-tallest player in NBA history.
During his first three seasons, Ming was one of the best centers in the league. Then in 2005, things began to go downhill.
Before the 2005-2006 season, Ming had only missed two games. Between 2005-2010, Ming suffered a string of non-stop injuries that severely limited his playing time.
Toe, back, foot, knee—if you can name it, Yao more than likely hurt it.
Because of all his injuries, the Rockets play Ming a maximum of 24 minutes per game in an attempt to look out for his long-term health.
If it weren't for all of his injuries and missed games, the sky would have been the limit for Ming.
The list of accomplishments that made Earvin "Magic" Johnson are far too many to list here.
However, his career will most likely be remembered by the Lakers-Celtics feud, and his friendly rivalry with Larry Bird.
In 1991, the entire world was shocked when Johnson announced that he had contracted the HIV virus.
While he announced his retirement when he held his press conference to regarding his illness, Johnson did go on to play in the 1991-1992 All-Star game, despite the fact that many players did not want him to participate.
Johnson went on to play for the "Dream Team" in the 1992 Olympics, but played infrequently due to a knee injury.
After a brief comeback the following season, he finally retired and made the move to coaching.
Between 1991-1993, Seles was the best female tennis player on the planet.
She won 22 out of the 34 tournaments she competed in, and made the finals in all but one of those tournaments.
Then in 1993, a rabid Steffi Graf fan ran out on to the court and stabbed Seles in the back in between sets in a tournament in Hamburg, Germany.
Although the wound only took a couple of weeks to heal, Seles didn't return to the sport for two years.
Once she returned, she was a shell of her former self. Although she won the Australian Open in 1996, this would be her last Grand Slam title.
When everything was said and done, Tennis Magazine ranked her the 13th-greatest tennis player of all-time.
One has to wonder if the stabbing hadn't occurred, where would she be ranked among the all-time greats today?
During his time at USC and Loyola Marymount, Gathers was a stud. He set multiple records in the WCC and at LMU.
During his senior season at LMU, he was considered to be a lottery pick in the upcoming NBA draft.
However, things took a change for the absolute worse during the 1990 WCC tournament quarterfinal game against Portland.
After nailing an alley-oop dunk, Gathers collapsed. He was rushed to the hospital, and was announced dead on arrival.
It was later discovered that Gathers suffered from a heart-muscle disorder. He was given medicine for it, but took it less than recommended because he felt it affected his performance on the basketball court.
As a tribute to Gathers, his teammate and long-time friend Bo Kimble shot the first free throw in nearly every professional game left-handed as a tribute to his fallen friend.
Lou Gehrig is one of the greatest baseball players ever to step foot on the diamond.
The original "Ironman" played an incredible 2,130 consecutive games, a record that stood for over 50 years before it was broken by Cal Ripken Jr.
In 1939, the captain of the New York Yankees was diagnosed with ALS, which has now become known as Lou Gehrig's Disease. He ended his career with a .340 batting average, 1,955 runs batted in, and to this day has three of the top six RBI seasons in MLB history.
On July 4, 1939, Gehrig address the crowd at Yankee Stadium with the most memorable speech in the history of sports:
Fans, for the past two weeks you have been reading about the bad break I got. Yet today I consider myself the luckiest man on the face of the earth. I have been in ballparks for 17 years and have never received anything but kindness and encouragement from you fans.
Look at these grand men. Which of you wouldn’t consider it the highlight of his career just to associate with them for even one day? Sure, I’m lucky. Who wouldn’t consider it an honor to have known Jacob Ruppert? Also, the builder of baseball’s greatest empire, Ed Barrow? To have spent six years with that wonderful little fellow, Miller Huggins? Then to have spent the next nine years with that outstanding leader, that smart student of psychology, the best manager in baseball today, Joe McCarthy? Sure, I'm lucky.
When the New York Giants, a team you would give your right arm to beat, and vice versa, sends you a gift — that’s something. When everybody down to the groundskeepers and those boys in white coats remember you with trophies — that’s something. When you have a wonderful mother-in-law who takes sides with you in squabbles with her own daughter — that's something. When you have a father and a mother who work all their lives so that you can have an education and build your body — it's a blessing. When you have a wife who has been a tower of strength and shown more courage than you dreamed existed — that's the finest I know.
So I close in saying that I might have been given a bad break, but I've got an awful lot to live for. Thank you.