In my experience, few things happen: often your height and weight changes from 15 to 18 approx., and jumps require various adjustments, and at the same time you become more aware of your body and more careful/cautious, more aware of the fact that a fall can lead to serious injury... when you're younger you don't think of consequence as much and just jump like a flea, but as you get older you think "no, I can't break this leg again, i have to go to work or to school in the morning".... and this fear also hold you back.....