Swimming, I used to swim in high school but I've been out of practice for a couple decades, I got back in the pool a couple of weeks ago and struggled to swim 500 yards which is something I used to do in 6 minutes so I've been going a few times a week and pushed myself to 600 yards the last few sessions, anyway I want to try for 1000 yards by the end of the year.
I second light blocking curtains and I personally sleep with a fan to drown out noise. I also take melatonin about an hour before I lay down, I used to take ambien but I couldn't handle the side effects anymore. I usually feel pretty well rested, at least enough for my shift.
Very unsuccessfully, I've been fighting this fight for over 30 years in and out of the care of doctors, luckily right now I have insurance so I'm just out copays and whatever fees the psychiatrist's office decides to send my way but it's worth it because I'm stable. Without professional help I pile on distractions, hobbies, overwork, volunteering, etc. Not a healthy coping strategy, I've tried to kill myself twice (the last time earned me a 4 day medically induced coma) and been put on psychiatric hold. I know you said poor people can't afford it but there are clinics where I live that deal almost exclusively with the homeless, if they can find a way to help them they may be able to help people in better financial positions who still can't afford treatment on their budget.
Edit: to address your question more productively, one of the things I've been doing on my own is writing to myself. I have been thinking about my situation and identifying behaviors that I need to change. When I go through my days I don't really consider my actions but when sit and really think about it I can see what I am doing that is toxic, then when I start to do it again it's easier to identify in the moment and attempt to alter whatever I would have previously done, e.g. when I am frustrated with something one of my kids has done I used to yell quite a lot, now I excuse myself to a quiet place, calm down a bit, and then go back to address their behavior. I haven't even seen my counselor since my last suicide attempt (less than 3 weeks ago) but I found that this has helped me immensely.
So they're frenched fries