Good times to do this:Just before bed
Lounging around in bed in the AM
during an endurance workout
resting after an endurance workout
during repetitive safe physical tasks (raking leaves, shoveling, washing car, brushing pool)
Some exercises to help you do this:
Basic mental flexibility:
the endless hum. Can you imagine humming a single node through the changing of your breath from in to out or vice versa. You may first think you are doing it, but if you really listen to your own imaginary voice you'll likely hear a short hitch. But one's mental "hum" need not be connected to the physical...
imagine greater resolution. Imagine a landscape scene with trees. Why aren't you seeing each leaf? Why not each vane on each leaf, and the stomata? Why is your imagination limited to your physical visual resolution?
not thinking. Stop the voice in your head. Stop telling yourself to stop it. Try thinking about breathing to stop thinking about other things, in, out, in, out, now stop saying in, out. Now stop saying "Yay I did it!" :-). See how long you can exist without linguistic thought. Try to make a decision without voicing it or acknowledging in voice that you made the decision.
"hear" in your mind a song in other people's voices. Not yourself singing it. Hear the actual instruments with proper tone color not you humming the melody. Hear multiple instruments. (this is probably quite easy for musicians but hard for the rest of us)
Workups to resting your mind in a problem:The key here is "resting" -- you are not trying to force something. Let your mind wander for creativity...
replay a novel. See the plot in your mind like a movie. If it didn't take hours you probably skipped parts. Go back and do it in greater detail. Multiple times greater detail. Stop verbally telling yourself you missed something! Practice first narrated visualization then no narration (visualization only).
imagine a flat endless plane. Put stuff in it. Let the stuff interact. Let other stuff come in that your "voice" didn't suggest.
Put thoughts about the problem on the plane, or replay them visually not in words. See multiple aspects coexist in your thought plane, let other stuff come in. If you get far off your problem let it go and see what comes up, maybe try to combine whatever came up with some part of your problem.
Later, when you assess, if you are never (say out of 10 times) able to stick onto the problem, but move to the same thing repeatedly, maybe your problem really isn't interesting to you and you should be working on the something else?
If you come up with a few good ideas, write them down right after the session (keep a pad by the bed)... if you fall asleep you'll have forgotten some in the AM probably. If this happens, you can sometimes recapture the idea(s) by resting your mind again (as soon as possible).