If you want to watch cartoons, hey, that's fine. It's your life. If I want to watch animation, I'll find a good anime, but not some kiddie show.
And Siouxz: I never said roller coasters were childish.
My young friend I have watched cartoons my entire life and sports as well. Both are thought to be worthless activities by some but both stimulate me and provide enjoyment thus they are worthwhile in my book. Watching them hasn't stopped me from pursuing studies of the most serious sort or being entirely up to date with the state of the world.
I appreciate a serious attiutude in a young person most are more concerned about having fun than anything. My boys were at your age but now are undertaking serious endeavors themselves. Have some fun though it will make you live longer. Cheers.