"Argh, right in the kidneys." Salary: $95,000

It was a rocky start, but at age forty, you're finally ready to start working under a board-certified nephrologist. "Hey," you realize, two months into the job, "this is really hard." Maybe it'll get better later?

"Great lecture, professor." Salary: $130,000

You finished all the requirements to become a practicing nephrologist, when suddenly it hit you, maybe it was school you loved all along. Goodbye hospital, hello tenure track.

"Elevator going up." Salary: $200,000

You work at the local clinic, which also happens to be the best hospital within a hundred miles. You're rising in the department, and doing some good research while you're at it. You're a little stressed, but the superhero feeling combined with the tidal waves of cash help with that.

"My nephrologist, my hero." Salary: $300,000

You're a partner at a well-respected private kidney practice, and you've done some great work over the years. You make your own hours, for the most part, and importantly, nobody is above you.

"Ka-ching-a-ling, it's the Kidney Man." Salary: $400,000

You rose fast. You owned your own practice by the time you hit forty, expanded healthily, and after truly earning it with decades of commitment, you've decided to take a step back, enjoy your family, and let the money come down like rain. It sure feels nice.