Stress
Yes, siree. There's sometimes a fine line between winning and losing a case, and it can eat you up inside until a verdict is declared.
Even if you aren't a trial lawyer, there's a lot of stress involved in preparing legal documents and having them filed by the deadlines, keeping your clients happy and convincing them not to call you every ten minutes, and worrying that one of your co-workers is going to take a spin in your big, comfy chair while you're out of the office.
And remember—for most of your work, you're competing against really good athletes. If you like that head-on collision feeling, you better be sure you've got the game to play in the league with seven-footers.