Free chapter from Dr. John Medina's book:

Rule #1: Exercise boosts brain power.

The human brain evolved under conditions of almost constant motion. From this, one might predict that the optimal environment for processing information would include motion. That is exactly what one finds. Indeed, the best business meeting would have everyone walking at about 1.8 miles per hour. Researchers studied two elderly populations that had led different lifestyles, one sedentary and one active. Cognitive scores were profoundly influenced. Exercise positively affected executive function, spatial tasks, reaction times and quantitative skills.

So researchers asked: If the sedentary populations become active, will their cognitive scores go up? Yes, it turns out, if the exercise is aerobic. In four months, executive functions vastly improve; longer, and memory scores improve as well.

Via Maggie Rouman