I know, it sound like bull and doesn't sound fun at all. But it really works. Get on the treadmill and it will get your brain juices flowing. When I run and walk for about an hour I get so tired I collapse on the floor. Then it's followed by a high where I start babbling and the ideas just come. This brings me to our next point…
Babble
If you alone, start talking to yourself. Anything you say at all will eventually turn into some great ideas. Or if you're with someone, talk to them…
Talk to Someone
Have a conversation with someone. Deep ones are the best for being creative, but it could be about anything, really. During the conversation just keep thinking to yourself, “could I use that?” You'll get some yes's guaranteed.
Go For a Walk
The fresh air and mobilization will wake you up. Just ponder and look around you. This one's a no-brainer.
Same Thing Goes For a Drive
Take a drive to nowhere and end up somewhere. Or go run your errands. Mainly, get out of the house or wherever you were when you had your brain-block. Change the scenery and be on the move.
What Not To Do
Watch television or read. I don't know if this works for some people, but I know when I watch TV or read, all the ideas I get are a copyright law suit waiting to happen. It prevents you from being original and tempts you to steal ideas.