As it turns out, physical exercise (running, walking etc) makes us less forgetful, help us study easier and can even keep old-age dementia at bay.

The Franklin Institute presents various studies and proofs why exercise and workout is necessary for a good brain. Walking can drastically improve your brain condition:

"Studies of senior citizens who walk regularly showed significant improvement in memory skills compared to sedentary elderly people.
Walking also improved their learning ability, concentration, and abstract reasoning. Stroke risk was cut by 57% in people who walked as little as 20 minutes a day."

Running, for younger people, is the best physical and mental exercise, because it can raise the number of your brain cells.

There's no excuse to skip your workout, even if it rains. Remember how much good it brings you, and stop being lazy. Your behind will get firmer, your cellulite will be less visible and your brain will be in better shape.