While most of us can't wait for retirement to come, the same can't be said for professional athletes. As we've seen, they do nearly everything they can to stay in the game for as long as possible.
Unfortunately, certain factors come into play.
It might be Father Time catching up to a player's body, forcing diminished play. Or maybe the team doesn't want him back because of injury concerns or a conflict with his contract.
Due to that, many of our favorite athletes have been forced off their teams rather than calling the shot on when to walk away from them—as Mariano Rivera and Andy Pettitte both did.
So while these 18 guys wish they could have played with their teams forever, their front offices just wouldn't allow it, forcing them out and into either retirement or signing elsewhere.
Go ahead and laugh if you want to, but the fact of the matter is that quarterback Tim Tebow has been pushed out of the NFL by teams.
As an accomplished college player—he won one Heisman Trophy and two national titles—Tebow had hoped to become a star in the pros too.
For a guy who won a league MVP award, took his team to the NBA Finals—in a series loss to the Lakers (2001)—and sits in the top 20 on the all-time scoring list, you'd think that some team wouldn't mind adding Allen Iverson to its roster.
The problem is that the only teams who seemed to want him were either overseas or in the Developmental League—and we all know that A.I. wasn't going to have any of that.
He formally retired a few months ago, coming to grips that his 11-time All-Star career was over for good.
I was sad for a lot of guys on this list for being forced out, but I think Brian Urlacher being shoved out the door and disrespected by the Bears might be tops.
After earning eight Pro Bowl appearances and a Defensive Player of the Year Award (2005) and supplanting himself alongside Dick Butkus and Mike Singletary on the Mount Rushmore of great Bears linebackers, the team should have treated Urlacher a little better than it did.
Unfortunately, neither side could come to terms on a contract for this season, which left No. 54 to call it quits in order to avoid playing for any other NFL team.
Drew Brees might be an absolute stud and a top-three quarterback in the league now, but before he started breaking passing records and winning Super Bowls, he was just an ordinary guy in San Diego.
After some inconsistency in his first two seasons with the Chargers, the team decided to make a draft day trade for Philip Rivers to make him the new face of the franchise in 2004.
It was only after Rivers held out into training camp that the Bolts decided to stick with Brees as their starting quarterback.
But even after leading the team to a combined 20-11 record in the next two seasons—and scooping up a Comeback Player of the Year Award in 2004—the Chargers let Brees walk after he tore his labrum in the final game of the 2005 season against the Denver Broncos.
It worked out well for him, as he signed a huge deal with the New Orleans Saints in 2006 and led them to a Super Bowl victory just a few years later.
After compiling 662 victories and a winning percentage of .735 in his 29 years for the Hoosiers—along with three national titles—legendary coach Bob Knight was given the boot by former IU president, Myles Brand in September, 2000.
With an enforced "zero tolerance" policy after allegations of Knight choking several former players, Brand relieved him of his coaching duties, enraging fans and students as they bid farewell to their coach one last time.
Sure, former French great, Zinedine Zidane, was 36 years old at the time of his famous head-butting incident in the 2006 World Cup final.
After receiving a three-match ban from FIFA following the red card—instead taking three days of community service—Zidane saved himself from the embarrassment that was certain to fly his way, calling it quits instead.
But hey, at least he got a statue in his honor last year.
Future Hall of Fame running back LaDainian Tomlinson found out just how much of a business the NFL is when he didn't just get pushed out once but twice by the only two teams he played for during his illustrious 11-year career.
The first time came in 2010 with his original team, the Chargers, who decided to release "LT" after his worst season of his career, which saw him rush for just 730 yards with a 3.3 average—though he did score 12 touchdowns.
Many attributed it to age—he was 30 at the time—yet Tomlinson believed it was a failure of the team to run the ball under then head coach, Norv Turner.
In the second instance, Tomlinson was let go after his contract with the Jets ended, which left him without a suitor who wanted the now 32-year-old.
After rushing for 1,194 yards and seven TDs in his last two years in New York, it was obvious that his time as a star had ended, forcing him to retire as the league's fifth all-time leading rusher.
Just as I mentioned being sad for Brian Urlacher for not being able to play one last season with the Bears, I extend the same sentiment to Paul Pierce and Kevin Garnett after they got traded to the Nets this offseason.
For Pierce—who ranks No. 2 on the all-time franchise scoring list and won a title in Boston—he openly acknowledged how he wanted to retire a Celtic.
In Garnett's case, he may have been a transplant who was acquired via trade back before the 2007 season, but Beantown grew on him, and he too had hoped to end his career in green and white.
Unfortunately, it didn't work out the way they had hoped, and they were left feeling forced out—and a bit betrayed—by the team.
As a Cleveland fan, I remember the days of Manny Ramirez being one of the greatest young hitters in the game and the youngest pup on a team vying for a World Series in 1995.
But as his career went on, he became more aloof than ever, making some questionable decisions that led to him exiting baseball.
Even after a resurrection with the Dodgers in 2009, "Man Ram" spoiled opportunities with teams afterward that took a chance on him—the White Sox, Rays, Athletics and Rangers—by testing positive for PEDs. He retired in 2011, before making a comeback in the few years following.
Although I don't remember seeing much of Marcus Allen play during his 16-year career, the highlights I've seen of him on TV are remarkable.
Currently sitting as the 12th greatest rusher in NFL history, winning a Super Bowl—and the game's MVP—and going to six Pro Bowls, Allen had a career that saw him inducted into the Hall of Fame in 2003.
But thanks to age and declining performance, Allen was more of a leader than anything in his last year in Kansas City—he was 37 that final season of 1997—as the Chiefs decided to move forward with a younger running back, Greg Hill, who they selected in the first round in 1994.
While Phil Jackson has more title rings than any other coach on the planet (11), he still can't do anything that he wants apparently.
That was the thinking of the Lakers following their latest championship back in 2010, who, after a contract dispute with Jackson, had the "Zen Master" leave the sidelines.
The same thing happened in 2004 as well, as the organization refused to match his asking price and saw him walk away for a few seasons before they turned to him again.
To put it bluntly, with Jackson engaged to Lakers executive vice president, Jeannie Buss, there will always be a Hollywood drama around Jackson returning to the sidelines whenever the Lakers seem to be underperforming.
Just as his former coach, Phil Jackson, got forced off the sidelines by the Lakers a few times, Hall of Fame forward, Scottie Pippen, experienced the same fate to end his career.
After winning six NBA titles with the Bulls in the '90s, Pippen bounced around with a few different teams before finding himself back in the Windy City for the 2003-04 season.
It didn't work out as planned though, as "Pip" was only able to suit up for 23 games—starting just six—before the 38-year-old got pushed aside for younger players on a team that was just 3-20 in the contests he played in.
After becoming the all-time *home run king in 2007, former MLB great, Barry Bonds, was told following the season that the Giants—his team for 15 seasons—would not be offering him a contract.
It didn't happen.
With the Packers committed on transitioning to Aaron Rodgers as their starting quarterback for the 2008 season after Favre announced his retirement, the team had enough of the waffling and let No. 4 walk away.
It didn't come without headache, though, as there was a bunch of drama with the Green Bay front office about getting his release to play again, with Favre even attending training camp after being reinstated to try and work things out.
Deciding it was time to part ways, the "Ol' Gunslinger" was dealt to the Jets and played a season in New York before retiring again and then making a comeback to join the Vikings for two more seasons to end his career.
Although I can't say I personally know the feeling, I'd imagine that any athlete who gets traded experiences the equivalent of having to see his ex-girlfriend as happy as could be with her new boyfriend via Facebook pictures.
If that's the right analogy, then Wayne Gretzky was hurt when his adopted hometown of Edmonton sent him packing to the LA Kings back in 1988.
After capturing four Stanley Cup titles in five years, Edmonton fans couldn't fathom seeing "The Great One" donning another sweater, but the realization came when he made his first return to Edmonton, receiving a standing ovation by the sold-out crowd.
Just as he was forced out of San Francisco after the Niners proclaimed Steve Young as their future starting quarterback heading into the 1993 season, Joe Montana found that the same thing was going to happen a few years later when he played for the Chiefs in 1993 and 1994.
Proving to be healthy in his last season in Kansas City when he started 14 games and led the team to the playoffs, Montana decided it was time to hang it up, handing the keys over to his backup at the time, Steve Bono.
His four Super Bowl wins (and undefeated title record) are only matched by the Steelers' Terry Bradshaw, making him arguably the greatest signal-caller to ever play.
After Jim Brown led the league in rushing in all but one season of his nine-year career—along with capturing an NFL title in 1964—one would imagine a team would be ecstatic about having arguably the greatest runner in NFL history back for plenty more.
But then Browns owner, Art Modell, took a hard stand against Brown when he was waffling between playing football and pursuing an acting career, threatening to suspend him if he didn't report to training camp.
With Brown losing the desire to play football, the letter from Modell only added gasoline to the fire, almost forcing him to turn his back on the franchise.
He's the greatest player of all time, but even Michael Jordan didn't get preferential treatment from his Chicago Bulls after winning the last of his six titles in 1998.
With a looming NBA lockout—and the front office's desire to prove it could win titles without coach Phil Jackson and supporting players, Scottie Pippen and Dennis Rodman—Jordan decided that it was best that he burst the air bubble in his Jordan shoes, saying he was "99.9 percent certain" he'd never play another game in the NBA.
If he was talking about that game being in a Bulls uniform, then he was correct, as he made a return to the league in 2001 with the Washington Wizards before saying goodbye for good in 2003.