You may be relieving other people's stress, but who's there to relieve yours? Performing such a repetitious job can be tedious work, and more wear and tear to your hands is never fun to deal with. Most massage therapists love what they do, but the job isn't entirely without its stressors.
There's also the stress of being independent. Especially if you've got your own practice, it's up to you to bring in your own clients—but wherever you work that's going to be an issue. Marketing and networking and date-setting's going to be time-consuming, and trying to build your contact list can be the most stressful part of your job.
On the bright side, at least you'll know where to go to get some great stress release candles and calming incense.