Barry Sanders was on the cusp of becoming the NFL's all-time leading rusher when he decided to walk away from the game in 1998.
It was Sanders' stunning exit from the game that provided the inspiration for this list.
Although the exact reason for his decision remains somewhat of a mystery, he has said he was simply tired of playing professional football.
Michael Jordan was tired of playing professional basketball when he walked away during his prime, choosing instead to pursue his dreams on the baseball diamond.
The actions of Sanders, Jordan and so many others has left us scratching our heads and wishing we could have seen more.
In some cases, athletes like His Airness have come back to deliver more spectacular moments.
In other cases, athletes like Sanders have stayed out of the spotlight for good.
Here's a look at 20 athletes who walked away too soon.
One of the greatest non-human athletes to ever live, Zenyatta came within in a nose of finishing her career a perfect 20-0.
One has to wonder if she really would have been retired had she won the Breeders Cup.
Before Candace Parker showed up in Knoxville, Holdsclaw was the biggest thing women's college basketball had seen in a long, long time.
She took her talents to the WNBA and played for eight full seasons before walking away.
He professional career was marred by bouts of depression, which contributed to her early exit.
Smith was one of the most productive running backs in the NFL and part of some of the most potent offensive teams ever assembled.
He decided to retire following the 2000-2001 season at the age of 29, saying he wanted to go out on top and possibly even pursue medical school.
By retiring abruptly, Smith left millions on the table as he prepared to hit the open market as a free agent.
Like many of the great athletes on this list, LaFontaine had little choice but to retire thanks to injuries.
A number of concussions forced one of the best young centers in the game to walk away after just seven seasons.
Dryden played just seven full seasons in the NHL, but he was one of the best goalies in the league during that span.
His all-time record of 258-57 speaks for itself.
Dryden walked away from the game at age 31 to pursue other interests, writing a book and eventually getting into Canadian politics.
Sayers was fast and graceful and seemingly destined to be remembered as one of the great runners to ever play in the NFL.
Then came a string of knee injuries that hampered and subsequently ended his career.
After suffering his first series injury, Sayers attempted to return before the end of the season without being completely recovered.
That determination probably cost him at least few more great seasons for the Bears.
Sorenstam is widely regarded as one of the best female golfers ever, with 72 wins on the LPGA tour.
She retired at age 37 with very little warning, saying she wanted to walk away to spend more time with her family.
Ricky Williams' bizarre life has taken him across the globe and in and out of the spotlight a number of times.
His mental struggles have been well-documented, but it was surprising when he walked away from the game in the absolute prime of his career.
After violating the NFL's substance abuse policy, Williams was heavily criticized for choosing marijuana over football.
Like many of his counterparts, he couldn't stay away for very long.
Another running back who had his career cut short by injuries.
Davis came out of nowhere to become the best player on the Broncos, rushing for over 2,000 yards during the 1998 season.
The success came at a price, as his heavy workload began to take its toll.
Davis never really recovered from a torn ACL, and decided to walk away from the game on his own accord before the 2002 season.
Dementieva became the latest great ladies tennis player to walk away from the game when she retired this fall.
Just a year removed from her highest ranking on the tour, she abruptly decided to walk away to focus on starting a family.
One of the greatest athletes to ever live, Jackson was headed to superstardom in both Major League Baseball and the National Football League prior to suffering a hip injury.
Jackson never managed to play football again, but briefly returned to MLB with the Chicago White Sox.
He was never the same following the injury, and retired with very little of the speed that had once made him a legend.
Depending on who you talk to, Jordan's jump shot and legendary pose to beat Bryon Russell and the Jazz in the 1998 NBA Finals might have been the perfect ending to his legacy.
Thanks to that odd return in a Washington Wizards, there will be no way to settle that argument.
There will also be no way to know what Jordan would have done had he not walked away.
There were plenty of questions that may have led to the dynasty being broken up even if he hadn't retired.
Ultimately, Jordan probably left a couple of NBA Championships on the table.
Jones decided to retire from professional tournaments at the young age of 28, although he did continue to play in the Masters for nearly 20 more years.
The consummate sportsman, Jones played a prominent role in expanding golf's popularity stateside.
He wasn't said to be overly skilled, but you get the feeling a better sample size would have furthered his reputation even greater.
At the age of 25 and at the absolute pinnacle of her game, Henin decided to retire to focus on her family.
At the time, she was the World's No. 1 player, making the move even more stunning.
She has returned to action after more than a year away from the game, but it remains to be seen if she will ever reclaim her place atop the rankings.
One of the most dominant pitchers ever, the legendary lefty was still only 30 years old when he began to suffer from arthritis in his shoulder.
Koufax briefly pitched through the pain, but ultimately decide to walk away despite having a few good years left.
The only undefeated heavyweight in history, Marciano fought for a short span and was completely overwhelming to his competition.
During his career, he won all 49 fights and posted 43 knockouts.
There is no telling what he would have accomplished has his career in the ring lasted more than five years.
Another incredible athlete, Brown retired after just nine NFL seasons to pursue his acting career.
Depending on how you look at it, his decision didn't make a great deal of sense.
The physical freak was the NFL's all-time leading rusher at the time of his retirement, and there's no telling what he could have accomplished had he played a few more seasons.
Borg retired at the young age of 26, in a move very few people saw coming.
During his career, he won 11 Grand Slam titles, including an amazing stretch in the late 1970's.
Borg captured five straight Wimbledon titles from 1976-1980, and four consecutive French Open championships from 1978-1981.
He briefly tried to return to tennis in the early 90's before calling it quits for good.
Simply put, Sanders was one of the most enjoyable athletes to watch in any sport.
His jittery moves helped make Thanksgiving dinner enjoyable, regardless of how competitive the Lions were during his tenure.
Like his reaction after scoring touchdowns, he exit from the game was very, very quiet.
In 1998, Sanders faxed a letter to a Witcha, Kansas newspaper to say he was hanging it up.
He surpassed the 2,000-yard mark in 1997, rushing for over 100 yards in each of the final 14 games of his career.
Some say Michael Jordan retired simply because he was bored.
Others say it was because he was fed up with Jerry Krause.
Others still say the NBA was growing tired of hearing rumors of his gambling addiction.
Regardless of why he did it, M.J.'s abrupt retirement rocked the basketball world and altered the course of NBA history.
Already with three straight titles, Jordan's Bulls were in their prime and prepared to contend for years and years to come.
Ever the competitor, Jordan quickly grew tired of failing in the Minor Leagues and returned to where he belonged.
Sadly, we'll never know what would have happened had he stuck around.