Scientific American reports:
Women who averaged 150 minutes of moderate exercise (golf, tennis, aerobics classes, swimming, or line-dancing) or 200 minutes of walking every week had more energy, socialized more, felt better emotionally, and weren't as limited by their depression when researchers followed up after three years.
While 150-200 minutes of exercise a week may seem like quite a lot of time for many of us, if you can break it into 4 times/week, we're talking about 45 minutes every other day. Or just 20 minutes/day if you can do it every day. That's a nice walk around the block or a mile or 2 on the treadmill.
These effects aren't likely to result in an immediate change in your mood, but could help over the longer term. As I say during therapy when I'm teaching behavioral activation, things like this can help put a floor under your mood so it doesn't go down too far. In DBT parlance, it's a way to reduce vulnerability to negative emotion.
Given my interest in using technology to aid mental health, I'm excited to see so many apps out there that can help motivate and encourage you in this lifestyle change. I'm currently trying one called FitStar and I've used a variety of tracking apps over the years. I'm very excited to see what the smartwatch space bring to us in this regard, as well.
All this is to say that you may not need a therapist to see some steady improvement in your mood. If you do, obviously we're here to help.
Good luck and get moving!