To keep the body in good health is a duty... otherwise we shall not be able to keep our mind strong and clear.
Buddha
The weak can never forgive. Forgiveness is the attribute of the strong.
Mohandas Gandhi
Admiration for a quality or an art can be so strong that it deters us from striving to possess it.
Friedrich Nietzsche
He who conquers others is strong; He who conquers himself is mighty.
Lao Tzu