Letting go of a good thing is really difficult.
For the MLB players mentioned in this piece, they've had tremendous success throughout their careers. Some have won MVPs, batting titles, Cy Young Awards and World Series titles.
But all good things must come to an end.
Without truly knowing a player's intentions at the end of a season, here we take a look at the ones most likely to retire after 2021.
DH Nelson Cruz, Tampa Bay Rays
Designated hitter Nelson Cruz made it clear back in February that retirement was not on his mind.
However, the 41-year-old has since been traded from the Minnesota Twins to the Tampa Bay Rays, where he has a legitimate opportunity to win a World Series.
Cruz has done everything else, so this is all that's left for him. He is a seven-time All-Star, the 2011 ALCS MVP, the 2014 American League home run leader, the 2017 AL RBI leader and a four-time Silver Slugger Award winner.
It's quite the resume to take home, especially if the Rays capture a title.
Cruz has post-retirement plans, though seven months ago said he's "not ready yet." Let's see if the final results of 2021 push him in that direction.
1B Albert Pujols, Los Angeles Dodgers
The fact that Albert Pujols and the Los Angeles Angels had such a public, ugly split speaks to a reality every baseball observer can acknowledge: the 41-year-old does not have a ton left in the tank.
He's slashing .238/.287/.442, compared to his career slash line of .297/.375/.544 and playing far less in a diminished role with the Los Angeles Dodgers. Playing less, in part, is what led to his breakup with the Angels.
Anywhere Pujols might go in the future will have the same conditions, with the hope of him being a quality reserve.
Perhaps his most significant contribution right now is having teammates use his bat to help them out of a collective slump.
It was working for Justin Turner, at least through about four games. He went 7-for-16 with a pair of home runs using Pujols' bat from Sept. 12-15 against the San Diego Padres and Arizona Diamondbacks, but since cooled off against the Cincinnati Reds.