Kobe has basically played over 21 seasons when you add in playoff games and whatnot. Along with coming in at 18 and all star appearances and Olympics and pickup basketball it's amazing that he has held up this long. Not to forget all the injuries that he has suffered over the years that he actually played through when he probably should have sat down. All that shyt starts to add up after a while no matter who the player is. Not to mention playing damn near 40 mins a night too. The reason why Duncan is still thriving is because Popovich wasn't scared to rest him during the season and was also conservative on his minutes once he hit about age of 30 while Kobe was still going hard even in meaningless regular season games.