The life of a baseball player is different than that of other pro athletes. As the cliché goes, baseball is a marathon, not a sprint. There are 162 games spread over 180-and-change days, and that doesn’t include spring training which many feel is too long as well.
The season probably goes quicker for everyday position players because they’re playing — wait for it — everyday. Starters have one or two days per week when they are full bore, but the rest of their time is spent recovering and gaming for their next start. The amount of down time is why the Atlanta trio (Greg Maddux, John Smoltz, and Tom Glavine) had handicaps about as low as their earned run averages.