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. We cannot instantly change our emotions by just “making up our minds to” – but we can change our actions. The sovereign voluntary path to cheerfulness, if your cheerfulness be lost, is to sit up cheerfully and to act and speak as if cheerfulness were already there.

Recommended reading: How to Stop Worrying and Start Living.