One of your most powerful sources of positive energy is physical activity.
Exercise is a potent anti-depressant and a natural antidote to the constriction and stagnation of depression. Your body is hardwired to move. The intricate connections among your muscles and bones, the flow of blood that carries oxygen and nutrients to those muscles, the intricate web of nerves originating in your spinal cord and your brain, all support your ability to walk, run, and lift heavy objects. Nature designed our bodies to move in ways that enabled our ancient ancestors to survive under harsh circumstances. As such, nature provided a reward-based incentive for engaging in strenuous physical activity: a flood of mood-boosting neurotransmitters.
For more info, please read my articles on exercise at Rodale.com: