Maintain a winning posture

Visualize a circus iron jaw bit hanging just an inch higher from the frame of every door you walk through.
On average, you walk through over 60 doors in a day. Practicing this visualization 60 times a day would turn this posture into your natural one.

Throw your head back and take an imaginary bite.
This will pull your cheeks back into a smile.

Imagine that it is lifting you, so stretch your body accordingly.
As you would hang by your teeth on the top, this would stretch your every muscle to the perfect posture.