Earlier quoted context omitted.
"Mental health" and "making an effort" are two dangerous terms to combine in the same argument. Just getting out of bed every morning can already be a big effort for many people with mental health problems, much bigger effort than exercise is for many sane folks; it should be appreciated as such.
Your point is taken, but one must remember that in the end we are all of us responsible for our own lives. There's a reason why people who lift joke that the heaviest weight in the gym is the front door. One approach that has worked well for many is establishing positive habits to displace negative ones. That takes a while, but there are tricks to help, like having a group to hold you accountable.
Depression is like I'm sitting on your chest and tell you that breathing is easy and all you need is to do it rhythmically.
Depression is like that day your brain doesn't function properly after not sleeping during the night, but every day for years and regardless how much you sleep.
Depression is not a bad habit, just like the flu is not a warm and fuzzy feeling.