I feel brave and strong.

Feelings follow posture more often than the reverse. Stand up, drop your shoulders, take one slow breath before a difficult call, and the body reports back differently — not transformed, but shifted a few degrees toward steady.

It's a modest effect and it is real. The nervous system takes evidence from the outside in.

Worth knowing on the mornings when brave and strong are not what you woke up as. You aren't required to summon the feeling first and act afterwards. Put the body where a braver person would put it, and let the rest catch up in its own time.