Al Horford wants to play until he's 40 years old, and in an era of hyper-athletic big men, that's an ambitious goal to say the least.
Horford, who has only just started to show signs of aging at 32, though, might just be able to pull it off. In earlier eras, it was a rare player who could last into their mid-thirties in any position, and big men tend to age the worst, then as now (Robert Parish stands out as a notable example from the Boston Celtics' past).