I have two safety rules for myself:
- No HackerNews/Reddit/... after 21:00.
- No computers/tablets/... after 22:00.
Other than that, other hobbies decrease computer time: watching series/news with my wife, running, cycling, Geocaching (a great outdoor hobby for the inner geek :)), and reading (generally newspapers).
Besides that, we are expecting our first baby next month. So, there will be no time for computers outside work ;).