I rarely finnish 100% in games, as I often can't find the motivation for doing so. When the story is over and the last boss is killed, I usually have a few days left before the motivation for playing the game is lost.
I also can't say that I've even played through the main story of many of the games I own, simply because I haven't had time. I have a bad habbit of buying a game when I find it cheap, and as a result I have more games than I have time to play. But I do intend to finnish all of them some day