You can go to the moon or walk under the sea, or anything else you like, but painting remains painting because it eludes such investigation. It remains there like a question. And it alone gives the answer.
The 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. To feel brave, act as if we were brave, use all our will to that end, and courage will very likely replace fear.