You are in the enviable position of being able to work for just 10 hours per week to support your quality of life. Perhaps you could pick a new hobby and dedicate your free time to becoming a master woodworker? Perhaps you could find a cause you care about and volunteer your free time to helping in some capacity? Perhaps you want to learn to paint or travel or meet new people or, hell, just sit in the park and feed the ducks.
Or if you really do want to do more income generating work, what do you want to work ON? Just saying "I should work more" isn't going to cut it.
> It is not enough to be busy. So are the ants. The question is: What are we busy about? - Henry David Thoreau