For years I have been using this system to focus myself while I'm low on energy or just flat out tired.

I call it the "fakir nap".

To start out you have to understand what I mean by "letting go". Close your eyes and think about anything other then what you are doing or where you are at this second.

Let yourself go, then as soon as you feel your self slip out, jerk your body and violently snap "awake" and act like your worried that you overslept. Go as far as to scramble for the time. If done right you will be fully awake.