The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!’ (I found it!) but 'That’s funny …’
Action seems to follow feeling, but really action and feeling go together; and by regulating the action, which is under the more direct control of the will, we can indirectly regulate the feeling, which is not.
Thus the sovereign voluntary path to cheerfulness, if our spontaneous cheerfulness be lost, is to sit up cheerfully and act and speak as if cheerfulness were already there. If such conduct does not make you feel cheerful, nothing else on that occasion can.
So, to feel brave, act as if we were brave. Use all of our will to that end, and a courage-fit will very likely replace the fit of fear.