You do realize that your body COMPLETELY changes chemically and hormonally during puberty, right?

On top of that, the stuff you do as a kid is fun only because it's new. At some point tag gets boring, backyard football where you score a touchdown everytime you get the ball and score 14 touchdowns during the half hour during recess get boring, trying new "dangerous" stuff like jumping your bike off something or jumping out of a swing....either the thrill is gone after trying it a few times, or you broke a bunch of shit and learned your lesson.

Not only do these things become boring, but you realize there's no point to it. As you get older, you become more logical (some more than others). Games have absolutely NO POINT to them, and as you get older things that are pointless aren't as fun because you're smart enough to know better. But even in your adulthood, you'll find the same pattern. The stuff that was fun when I was in highschool annoys me now, the stuff I was doing in my early 20's, I have no interest in now. My interests are changing once again, and hardly anything that kept me entertained has the same affect on me today.

For me, personally, I've found patterns are what make me uninterested in things (games mostly). When I was a kid, it was fun to take a football, and run the SAME ROUTE everytime to score a touchdown....I just outran people. It was fun playing baseball with my friends when I could hit a homerun EVERY time. Because I didn't realize I was getting a "gimme" everytime. I could repeat it over and over and over again, and be completely oblvious to the "pattern" I discovered and repeated. Now I don't have fun with anything that doesn't challenge me.

Maintaining a career, balancing finances, planning out vacations and nights on the town....doing all of that stuff by myself is more challenging than any game I play anymore. I'm sure I'll find new challenges to take on a decade from now.