Go into the sport because you have fun doing it, not because of 'what ifs' and dreams of gold medals. That way, no matter what happens, you win.
You have to remember that no matter how big your goals or how many you have, there are going to be times when you miss by a little bit. You have to be realistic and flexible. One reason I have so many smaller goals is that even if my big goals don't happen, I've still achieved so much along the way, I don't feel the loss.
Gymnastics is the type of sport where you can't take something that gives you more energy. Something may be great for the vault, but then you have the bars after it and you have to be more sedate for that.
If you can't handle all the injuries and scars, choose a less demanding sport.