The fall only comes later when all your having fun leads to a lot of not having fun (work piles up, relationships sever, projects fail etc.) I find living in a certain amount of fear of fun is healthy. If I feel like I've been having fun for too long, I've probably been neglecting something important that is going to really ruin my fun later.
I say all this, as I scroll through HackerNews looking for hits of dopamine instead of continuing trying to fix the CI issues that have been paralyzing my work for almost a day now. That's not good to be a fun conversation in my 1-1 if I ignore it for much longer...