Concentration - Most important Skill for Sportsman?

This largely depends on what you consider a sport Is chess a sport or simply a board game exercising one's logical brain? Some people/cultures consider chess a sport while others don't, and for good reasons. Anyway, in the case of chess, concentration is an absolutely must-have, but this skill is less important for a weightlifter who requires strength and form to lift the weights. I think to be successful at any sport, you need to learn the rules, practice, learn special moves, and, perhaps, get a coach to give you additional training. By doing these things, you build the right mindset that'll make you succeed.