I've been in a similar situation, and my reaction was to spend several months looking at the science of happiness, and thinking about what really makes me happy

I've been in a similar situation, and my reaction was to spend several months looking at the science of happiness, and thinking about what really makes me happy. I came up with some answers (time at home, time with family, a feeling that my work does more than make a few wealthy men slightly wealthier.) From there, I started working on a business plan, for a startup where the primary goal was to find a way to monetize the activities that bring me happiness. I can't say that this startup is currently profitable. It's not. But I'm executing on the vision, and so far things are very close to the plan. And I'm much, much happier than I used to be.