What if he doesn’t want to be an athlete? He’s 2. What he wants to be when he grows up will bounce back and forth many times before he is old enough to make a lasting decision.
In my opinion, you would be better off giving him a solid foundation to be successful in whatever he wants to do, rather than trying to make him into something he may have no interest in becoming. Teach him to use visualization, affirmations, and afformations. Give him a guardian spirit to watch over him, and cast general success spells, until he decides on a specific path, and then you can tailor the magick to his needs.
Magick is most successful if applied to enhancing skills someone already possesses, so wait until he’s older and see what talents he has and apply the magick to a career path that will use those skills. He can be successful in anything if given the chance. Don’t try to give him talents just because you think he has a better shot at success with them. Gifted athletes are a dime a dozen and very few of them are successful at the pro level.