Children can get plenty of exercise without struggling against each other. Cooperative games allow everyone to work together, without creating enemies. Again, an objective standard or one's own earlier performance will do. When Orlick taught a group of children noncompetitive games, two thirds of the boys and all of the girls preferred them to games that require opponents. If our culture's idea of a good time is competition, it may just be because we haven't tried the alternative.
Competition is actually destructive to children's self-esteem.
It interferes with learning, sabotages relationships and isn't necessary for a good time. There are no easy answers here. Children can be taught about competition, prepared for the destructive forces they'll encounter, without being groomed to take part in it uncritically. They can be exposed to the case against competition just as they are taught the harms of drug abuse or reckless driving. You will have to decide how much compromise is appropriate so your child isn't left out or ridiculed in a competitive society.