The thing I am seeing with depression is you can’t ‘mentally battle’ it. It’s not chess or football. It’s not something you can outthink. Exercise definitely helps, but it is not a ‘cure’. Depression is like having your thoughts laced with small doses of cyanide. You can’t swallow these thoughts. You can’t play with them or dissect them. They are dangerous and you can’t defeat them. The only thing that helps is being mindful of them, observing them, and then letting them go. Mindfulness might be a natural medicine to deal with owning a mind.