The types of stimulation I found most helpful are those that help grow the brain - meaning reading self help books or even watching
TED talks on their site.
Drawing also helps to work things out because I can see what I think (when I'm at work).
How it feels like when it's refreshing is that I don't feel fatigued afterwards and wanting to do more. My therapist worked out with me that there are activities that replenish the brain, and others that drain it.