Human bodies are designed for regular physical activity. The lazy way of much of modern life probably plays a massive part in many people suffering from depression today. Many studies show that many depressed patients who start aerobic exercise improve as much as those treated with medication. Exercise also appears to prevent depression and improve mood in healthy people. Many exercise forms — aerobic, yoga, weights, walking, running and more — have been shown to benefit depression.
Typical therapeutic exercise programs last for eight to 14 weeks of 3 to 4 sessions per week, of at least 20 minutes each. But you will find results as soon as you start exercising. If you suffer depression and anxiety disorders, exercise of more moderate intensity, like brisk walking, are more successful than more vigorous activities.
A lot of people prefer exercise that occurs in the course of doing some productive activity such as gardening, bicycling to work, doing home improvement projects and so on. They find it far easier to stick to activities like this than to lifting weights or running on a treadmill.