Depends what kind of doctor. Working in a clinic and seeing patients doesn't seem that hard much of the time, unless there are serious issues. Many doctors just check the basics and get you out of there.
For lawyers, rich clients are tough to come by, and even then you have to win cases. There are lawyers who take massive loans to gear up for trial, paying for help and expert witnesses and so forth. Tons of pressure.
Like somone else said, any reasonably smart person can pass law school. Passing med school is far tougher.