I look at improvising as a prolonged game of chess. There's an opening gambit with your pawn in a complex game I have with one character, and lots of side games with other characters, and another game with myself - and in each game you make all these tiny, tiny moves that get you to the endgame.
A healthy body means a healthy mind. You get your heart rate up, and you get the blood flowing through your body to your brain. Look at Albert Einstein. He rode a bicycle. He was also an early student of Jazzercise. You never saw Einstein lift his shirt, but he had a six-pack under there.