One of the most freeing things for me is Life Drawing. It's like exercise, an opportunity to shut off the brain for awhile and enjoy a more intuitive way of looking at things. When I draw from life, I try to make as direct a connection between my eye and my wrist as I can.
I like to use Conte sticks (to keep me from being detail-focussed), but lately I've been using charcoal pencils such as Ritmo. Check out my good friend & colleague Ron Lemen's page. He's the real master.