[twobyfour]

All the time. The solution is usually mindfulness. When you're lost in HN at 2AM when you should be sleeping (or when you're coding and in the zone), your focus is _inside_ what you're doing. You won't stop doing it until you pull your focus back and look at _what_ you're doing. That allows you to assess whether it's what you want to be doing _now_, and whether it's a good use of your time.

To prompt yourself to pull your focus back , you can condition yourself to respond to certain cues - typically sounds - and program your phone or computer to produce those cues every N minutes. Meditation can also help develop your ability to be mindful of what you're doing and why instead of getting caught up in the moment.