Almost two years ago I left my relatively well-paid job as a secretary in a large accounting firm and about a year and a half ago I started in a similar role at a university. My new job pays about 65% of what the old one did. For the first 10 months I only had a 20 hrs/wk position though, so it was more like about 40% of my old salary. But feeling like I'm supporting something important, that really could make a difference in the world (education) has made a huge difference to me. I'll probably never FIRE, although now I know that it is possible to live on very little so going back to part-time at some stage is entirely possible and I don't feel hopeless or like I'll never be able to retire. But that thought is not entirely unbearable anymore. Bad days are now just random bad days. Before, bad days felt soul-crushing. I'm currently going through a period of mild depression and even so, bad days don't feel the way they used to.
To make up for some of my lost income, I also now translate as a side-gig. I was lucky enough to be approached last year by an institute that is involved in peace research and now sometimes do work for them. Working all weekend is still strenuous, but during the last few very busy weeks, for example, I found myself able to keep going and be enjoying it even when I was exhausted. I'm not necessarily making a difference to the world but I certainly find it easier to put in lots of hours translating documents on potential solutions to situations in war-torn countries than translating, say, a legal opinion on how some giant corporation can get around paying tax.
What "makes a difference" means can, of course, be different for everybody. And some people may be genuinely unaffected by or uninterested in thoughts of whether or not their job makes whatever they consider to be a difference. But for some people, like me, it's really important.
Yet having said all of that, if I were to win the lottery (not very likely, since I rarely play)/achieve FI, I probably would leave my job. If I have to work (for financial reasons) then I need it to be something that makes a difference. If I don't actually have to work, then I have a huge list of things I would like to do that would make my life meaningful in other ways.