How do I become a better and faster thinker?

lately i've been losing my mind, literally, and believe me, its much much horrifying than it sounds. I have hard time focusing, my mind drifts and wanders off so much. its like hyper case of ADD or something, but i don't believe in ADD or diagnosis like that. anyways.....what are great ways to renew my mind and become smarter and thinker better? Nature? Books ( like what?), TV, Video games, ? Suduko? IQ test? help me out plz?