I think the unfortunate reality is that there is no magic bullet solution, no matter how much we wish there might be. All the hacks and medication in the world aren't going to solve the societal problems that cause us the most distress. Vyvanse might help me fold my laundry, but it's not going to change that rent is due on the first and if I'm late to work again I'm going to get fired
Depression really is its own bag. I'm not in medicine, but frankly I think it's more of a symptom than a disease of its own. It's comorbid with ADHD, autism, PTSD, compulsive disorders, anxiety, gender dysphoria, poor diet, and even just living under the constant pressures of the modern world. We have medications to manage the symptoms, but a lot of the time they're a crapshoot and without treating the underlying cause you really aren't likely to show improvement.
I also think treating depression is prone to a cart/horse problem where people confuse cause and effect. Anybody who has suffered from depression probably knows and was infuriated by the advice that if you just get out of bed and exercise then you won't be depressed. Then one day you get out of bed and exercise and don't feel so depressed. The outside observer sees the exercise and concludes that it cured your depression. They don't see the countless hours of therapy, the constant reframing of problems, the restructuring of your life to accommodate self care, the medications that got you to that point, etc
It's beyond naive to think that some pushups and going for a walk cures depression, but having experienced it for yourself you might even conclude that was the case. But I posit that you were able to get some exercise only because you were less depressed than you were before, and something else had to happen to get you to that point. It's tempting to look at the data that shows the correlation between people who exercise and people who are depressed and conclude that a healthy lifestyle fixes depression: but another interpretation is that the people who are depressed can't lead a healthy lifestyle.
Personally I think that's where a lot of the well-meaning advice is helpful but also totally misses the mark. People will say (or insidiously get paid to say) that something helped them and it brought them out of the funk, but it was probably a myriad of things that working together helped elevate them to a point they could take back some control over their life. There's a million billion articles about whatever self care fad is a miracle cure, but if it does indeed help then it's just a piece of the puzzle.
Pessimism aside, self care is pretty important. But it's also personal, only you know what truly makes you feel better. My experience is that if you do anything specifically to make yourself feel better without forcing yourself, then it probably does help you feel better. We're tempted to look at the action (taking a bath, reading a book, putting your phone away), but it's really the intention that helps (I want to feel better, so I'm going to do something to feel better). It's a mental problem with a mental solution, and while that solution might be mercurial or difficult to take hold of, it's the best tool I've got.
Anyway, rant aside: I also hate that the solution to being depressed is to not be depressed. It's doubly extra super frustrating that my best advice also boils down to "stop being depressed," although I hope I've framed it in a way that shows that it's not as simple a solution as it sounds