If your custom is to take walks, you should intend it for the sake of heaven — in order to be healthy for the service of God, blessed be He. Your thought should be that you are exercising so that your mind will be relaxed and vigorous, so that you will see how to act in all your affairs as is proper [that is, psychological health]. (Avodat ha-Kodesh, Moreh b'Etzba, 3-123)
— Avodat ha-Kodesh in Jewish Spiritual Practices