It is important and essential for me to be able to stop and do nothing.
For example, you had a hard day at work and now you are exhausted, but when you are sitting on the bank of a/the river and enjoy beautiful view, keeping silence can really help you. Then in the one moment you understand that in any event everything is good, and just after that you feel new strength to go ahead.
In short, my advice is silence, a picturesque view and may be some good wine
What helps you when you are tired?
Maybe sex. Drugs (I may be jumping to conclusions, it's just because "Sex, drugs & rock'n'roll" are pretty much idiomatic; I'm sure there are people out there who relax when they wear drag ;}). Rock-and-roll?)))
I tend to go for a run if work has me knackered. Then blob in front of a good movie with a nice glass (bottle? =D) of wine.