Losing Motivation because of Mental Health Issues

I have signed myself up for FB Reach and FB Bodyweight 2 as a beginner. I want to get into it, but I suffer from mental health issues. A few days a week it hits me hard, and I stop working out, taking a break day. I then proceed to eat my depression and stress away, and then I have no energy to exercise. I can't get in to these workouts, I loose motivation pretty quick. Mental health is an ongoing struggle, and it affects several parts of my life.

I was hoping exercise would help with this, but if I can't start exercising, it can't help. What should I do? Is exercising and staying healthy just not my thing?