Resting
One of the most undervalued components of improving one's mental health, is simply not trying to improve one's mental health. It may sound counterintuitive, and likely that's why people don't talk about it as much as they perhaps should, but I think it is absolutely vital in order to bring about a marked difference to your wellbeing over a long period of time.
The reason is pretty simple - trying to become a better, healthier person is exhausting. By nature, people who struggle with mental health issues tend to find themselves fairly tired most of the time anyway, so piling on the extra emotions of struggling to change will only make this worse. If you push yourself too hard, you'll burn out, just like with anything else.
Sometimes it's OK to struggle, to procrastinate, to be sad, to do things you shouldn't - that's human nature. Not everything has to be about overcoming your issues and obtaining enlightenment - on some days, you can say "hey, I've made a lot of progress recently. Today I'm just gonna rest, and not do anything scary", and I wish more people talked about that.
Try and become a better person during the week. On the weekend, just enjoy being who you are.