For some professional athletes, it's a difficult task to decide when it's time to call it quits.
Some guys, like former San Antonio Spurs big man David Robinson, know when it's time to go.
Others, like the NBA great and MLB failure Michael Jordan, just can't give up their beloved game.
Luckily, for the following MLB players, we're doing the work for them.
Here are six MLB players who will (or should) be calling it quits following the 2013 season.
Jim Thome has been around the block once or twice, playing for six different major league clubs during his iconic 21-year career.
Thome owns a career on-base percentage of .402 and sports 612 homers, and the 42-year-old has never been connected to steroids—pretty impressive considering he played straight through the steroid era in baseball.
The 2013 season is fast approaching and Thome has been left without a team to play for, which could signal his retirement.
He hit eight home runs last year in 163 at-bats split between the Philadelphia Phillies and Baltimore Orioles, but apparently that wasn't good enough for a team to come looking for his services this season.
In my opinion, Thome is Hall of Fame worthy and should go down as one of the best to ever play the game during this era.
It will be one of the saddest days in baseball when Mariano Rivera calls it quits, and unfortunately, I think that time is coming after this season
Mo is the greatest closer to ever toe the rubber, boasting an MLB-record 608 career saves—a number that's sure to increase by more than 30 following the 2013 season.
The 43-year-old has made it known that retirement is in the near future, saying that he will make an announcement regarding his future before this season begins.
The all-time saves leader is slated to return to the field in 2013 after missing most of last season with a torn ACL suffered while shagging batting practice balls in Kansas City.
It's a day that no baseball fan wants to see, but we need to prepare ourselves with the thought that Rivera will be out of the game soon.
Scott Rolen is one of the best third baseman to play the game, but after turning down the Cincinnati Reds' spring training invitation (h/t ESPN), it seems that retirement is on the horizon.
Rolen had a solid 16-year career, owning eight gold gloves, seven All-Star appearances and a World Series ring in 2006 with the St. Louis Cardinals.
The 37-year-old has been plagued by chronic shoulder problems and back spasms, which will likely lead to the end of his career.
He hasn't officially announced his retirement just yet, but you can likely expect it sometime in the near future.
Kudos, Mr. Rolen.
In my opinion, Todd Helton is one of the most underrated players to ever play the game of baseball.
He's a career .320 hitter with more than 350 homers to his name to go with five All-Star appearances.
The three-time Gold Glover will turn 40 in August of the upcoming season and played in just 69 games in 2012 before a torn labrum in his right hip forced him to miss the rest of the season.
The former NL batting champ hit just .238 last season and saw his power dramatically decrease to just seven long balls.
Troy Renck of the Denver Post reported back in March 2012 that Helton hadn't thought about retirement, but that was of course before the hip injury that forced him to miss more than half the season.
Following an exciting season with the Bronx Bombers, Raul Ibanez jumped ship to the Seattle Mariners, where he began his career.
It seems like the perfect full-circle approach for the 40-year-old to call it quits after this season.
Ibanez signed a one-year deal with the Mariners (per the New York Times) and will turn 41 at the beginning of this upcoming season.
The former All-Star is a career .278 hitter with a .340 OBP, highlighted by four seasons with at least 21 homers and 103 RBI.
Ibanez put together a solid 16-year career, but I think that career is coming to a close following the 2013 campaign.
Jason Giambi should have called it quits after his seven seasons with the New York Yankees.
Steroids have all but broken down the 42-year-old's body, as the former slugger hasn't played in more than 102 games or hit more than 13 home runs since leaving the Yankees.
It's clear that the former AL MVP's career is coming to a close, as the Cleveland Indians only signed him to a minor league deal for the upcoming 2013 season, according to the Washington Post.
The Indians are hoping the five-time All-Star can provide the lineup with some power, and that very well may happen, but along with Giambi comes a slew of strikeouts and a low batting average.
Giambi's career will forever be stained by his use of steroids in the BALCO scandal.
It's time to call it quits, Jason.
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