Yeah, maybe a test could be: How much do you enjoy the time actually working on something vs the time going home and enjoying the things your wage enables you to have.

Or as the sibling comment said, do you enjoy the vocation or the vacation more?

(Everything in moderation of course: Even the most interesting and meaningful project will turn into drudgery to some degree, simply due to the amounts of time involved. Also we're in the attention economy, so there are lots of things specifically designed to feel more rewarding in the short term than to work on a long-term project. Maybe the difference is how much meaning and reward there still stays besides the day-to-day drudgery)