Dancing's not always stressful, but I always make sure that I'm prepared as I can be, both physically, mentally, and practically.
Young dancers are training at a very vulnerable time in their lives, through adolescence, and while they are trying to work out who they are as people, never mind as a dancer. So train the whole person, not just the dancer.
I always recommend a sensible diet, including lots of carbohydrates and avoiding too much fat. Dancers don't need different fuel from other people - they just need more of it because they use more energy.
It's another myth that dancing distorts or destroys your feet. If you have the right shaped foot to start and a good, strong technique, your feet should be fine.
Franklin D. Roosevelt