I'm one of them.
My name is Viktor, I come from Ukraine where I learned how to tune pianos from my friend Pavel who is one of the best piano tuners in Ukraine right now. I started this exciting career in 2000. Tuning/regulation/rebuilding can be no stress job if you're confident in yourself and know what you're doing; it is for people who like music, like to solve problems and also have good hearing. A person can be born with good musical hearing or it can be achieved through exercising.
More info from wikipedia: http://en.wikipedia.org/wiki/Piano_tuning