Dealing with a client at work who is going through this. Severely depressed, suicidal tendencies, will not exercise despite knowing it has helped him in the past. He knows what he needs to do, but we also know damn well that he’s going to go straight up to his room and play video games all day.
Motivating is extremely difficult when it comes to severe depression. You can’t just point out what they need to do. Doing so will likely just deepen their depression because they already know. Getting people to understand that not every brain works the same or responds to the same kind of reinforcements is incredibly frustrating.