Paul F is right. I did 6 years after retirement (65 here) working three days a week. Job was interesting (maintenance repairs) but after that time I had the same feelings. I just got sick of trying to please everybody all the time. So finally left and don't know how I found time to do everything when working. It is a nice feeling, sort of like a looong holiday. I still feel weird when being with working people (feeling guilty) Hah Hah.
I am working on about 5 projects at the moment, supposed to be part time doing 24 hours a week but end up closer to 40, at least I get paid by the hour and have a 40 hour limit like the full time workers but even working full time I get behind, I woke up at 2am one morning last week thinking who do I want to annoy this week by not meeting their deadlines as I can't get everything done for everyone. Woke up later on with the Rick Nelson Garden Party song in my head singing "You can't please everyone so you might as well please yourself.". I was thinking was retiring again "Pleasing Myself", it seems to fit.