It’s so godd*mn frustrating isn’t it? All this crap that’s supposed to fix mental problems just not working. Exercise. SSRIs. Going outside. Meetups. I’m sick of feeling depressed, isolated, stuck in a rut, living a meaningless existence only to be told to do some activity for 30 min to take my mind off it.
I think the solution may be, as you touched on in your OP, to have a purpose. Also having a community. It has been shown in studies over and over again that happiness is strongly correlated with meaningful relationships.