Do nothing!

As composer, musician and producer Brian Eno has opined: "The difficulty of always feeling that you ought to be doing something is that you tend to undervalue the times when you're apparently doing nothing, and those are very important times. It's the time when things get sorted out. If you're constantly awake work-wise you don't allow that to happen."
http://blogs.hbr.org/johnson/2011/07/go-ahead-take-that-break.html