Think about it... Numerous studies show that exercise is good for the phyche. A 30 minute walk each day can be the salvation for someone suffering from depression. Personally, I know my mood is affected after a few days of not working out. People around me know when I haven't been running. I even read a story once about a psychologist who takes his clients for runs. And it works!
Everybody knows that exercising is good for physical health, but many people still do not exercise because of various reasons. But there is no good reason not to exercise. It's OK start small with just 10 minutes of walking. The beauty of exercise is that it will lead into better sleeping and eating habits, which also contribute to better health. When you exercise, you feel like eating food that is good fuel for your body. When you exercise, you have an easier time sleeping and you crave sleep.
If I encounter anybody with problems or who has a loved one with problems, the first thing I ask is: "Are they exercising?" If not, that is the place to start.
Everything else will follow...