Stress
The life of a physician doesn't come without its difficult days. In this case, there's some extreme susceptibility to "burning out." People burn out in a lot of careers, but there are a few extra stressors in this field: too many hours at work, too many bureaucratic tasks, and too many can't-be-unseen issues with other peoples' nether regions.
You'll work a lot. Once you're fully immersed in the urology racket, make sure you're taking sufficient vacation time to get away from it all for a while. Remember all that money you're making? Make sure to bestow a lavish gift upon yourself from time to time—there's no reason you can't have a Ferrari and a yacht.