There's the as if principle by Richard wiseman which I like and find useful.

The idea is if your body does the act of the effect you want, you end up as having that effect.

Example. If your tired right now, if you look up at the ceiling, the sky with eyes wide open, 15+ seconds then you will not be tired.

Same if you want to be tired, you can look down 15s and you will be.

Same if you want to feel hyperventilated, you can consciously breathe fast. And if you want to slow your heart rate, you breathe slow.

If you want to be happy, you can smile or laugh.

So many weird things one can do that actually is related to our body's posture and activities.