Use external triggers to get into a flow state
To enter the flow state, you must be willing to risk rejection and humiliation (as a lover), physical harm (as an athlete), etc., and continuously push on with your goals.
Be willing to fail.
Failure is inevitable. If you wish to enter this state, you must be willing to fail, look foolish and fall flat on your face.
Use the rich environment triggers.
You could seek complexity in nature, like staring at the night sky, or using technology to induce wonder, like surfing your city with Google Earth. You could also mix things you usually do, like brushing your teeth with the wrong hand or driving on a different route from work every day.
Use deep embodiment triggers.
Examples include practicing zen walking meditation, attending balance and agility training, and playing video games.