I'm pretty sure I solve some of my biggest problems while I let my mind wander on my ride home. It can be intimidating at first so I don't recommend immediately hopping on a bike and riding in traffic, but take a few weekends to get a feel for the bike of your choosing (lots of great commuter bikes out there) and then slowly get used to riding with cars zooming by you.
I've been doing this for a few years now and have never had more energy at work.