because you don't have the same amount of free time as before.<p>When you are a kid, all you have is a little bit of school. And then most of the day is free to do whatever you want.<p>When you are an adult, you work from 8 to 6(counting commuting). You come back from work, you don't relax, you go cook yourself dinner. Then you eat your dinner. And have 3 hours of relaxation before you go to sleep and repeat the process. On weekends? You go to home depot, you go through the mail etc.<p>As a kid, you might have 30 hours of "free" time when you have nothing to do. While as an adult, that number might be 5-6 hours, since you have so many more obligations.