Amen to tangible evidence! I feel similarly about my current career, but there are two things to keep in mind: the grass is always greener, and you can do something on your own terms (hobby) that fills the same niche. Thus, woodworking, or even painting, volunteering, etc.

As for the grass being greener, it's important to keep perspective about what the former was. I think your example re: bodily fluids is a pretty good example :)