I used to play a lot of online games from the time I was 15 to 18. I would play during week days, i.e more time on games than homework, and play hours on end at the weekend. Then all of a sudden I just got bored of them. I'm only 19 now but almost never play, even in the last month I only played 30 minutes of 1 game. I've got more involved in outdoors and sports like rugby because I've found it pulls me out of depressive moods (hitting people is fun xD).
I still spend more time on my computer than I should though :P