I would say have days or weekends where you completely don't think about game dev or whatever it is you are trying to accomplish. It sounds like such a simple idea, but it seems to work for me. When you can fully relax or do something enjoyable without having that guilty burden looming over your head of "Oh I should be working on something", it allows you to fully enjoy your leisure time while also kind of recharging your batteries for the thing you want to focus on.