This is why part-time doesn't work for most of us. When you hit these walls you know (unconsciously at least) that you don't really have to keep going. Giving u

This is why part-time doesn't work for most of us. When you hit these walls you know (unconsciously at least) that you don't really have to keep going. Giving up is always an option. So the fix is simple: make it more painful to give up than to keep going. Your inborn human psychology will take care of the rest. You can try to treat the symptoms, but I think that's the real root of the problem. It's definitely one I've faced myself and know a few people well enough to know it was a problem for them.