12crs
As Pegasus says there are many resources available and each person's sensitivities can make different areas more favorable.
I also feel the difference in my mental outlook on days I exercise for 20 minutes and days I don't. I still have days I don't do much exercise but usually on the second day I feel much more stable after exercising.
Food is a very personal choice we make. For years I had a high carbohydrate diet and when I finally started to modify that with more protein (vegetable or animal) then my mood swings due to blood sugar changes became less and less.
These suggestions are not meant to replace professional help or medicine, but reflect lifestyle changes that I found improved my overall emotional stability and feeling of well being in addition to other help I received from others. It also gives me a greater sense of having tools in the toolbox when things happen unexpectedly.