Doctor?

Three medical students were discussing what specialties they were planning to go into when they finished school.
One said, "I want to be a brain surgeon. That's the frontier, the cutting edge of medicine, where so many discoveries are being made."
The second said, "I want to be a heart surgeon. There are so many people who need that kind of help; look at all the good I could do."
The third said he wanted to be a dermatologist. When the others had finished laughing, they asked him why on earth he wanted to be a skin doctor.
"Listen," he replied. "Your patients never die, they never get well, and they never get you up at night."