Grad school can be rewarding, but you HAVE to love what you do.
If you think applying is stressful, wait until you get in your first class and realize that while you were the smartest guy/girl at your college, you're now the student who has to read and re-read and re-re-read in order to figure out what's going on. That will be unbelievably stressful until you have to teach your first class (most grad programs in my discipline have students teaching from their first semester). You're 22 years old teaching a class full of people that are your age or older (because no one is going to give a grad student a primo class, so you get the remedial or introductory-level classes) and who don't want to be taking the class you're teaching.
But that's not stressful compared to comps, which are some combination of oral and written exams, upon which you are told your future in the profession depends. Fail, and there's no Ph.D. for you. Pass, and you get the stress of writing the dissertation proposal, and being grilled in front of a room full of professors who are looking to make sure that you are actually competent to do what you say you want to do. Once you're through that, the dissertation is actually great. People leave you the f@$! alone and you get to write. But the dissertation defense sucks. Your advisor won't let you defend if they don't intend to pass you, but they will go out of their way to make the defense 2 1/2 hours of living hell.
Then you get to go on the job market. You haven't know stress until you're on the job market. Unless of course you get a job, and then it's the tenure track, and people have written books on the peculiar hell that is the tenure track. These days, though, it seems like American universities are trying their best to get rid of tenure and are certainly not hiring much, so odds are astronomically good that if you're getting a Ph.D. in a humanities or social science discipline, you won't be getting the job that you've spent the last 6-10 years training for, but will be cobbling together a series of part-time jobs in order to make a subsistence wage.
I'm speaking as someone who's been extraordinarily fortunate, and who has just gotten tenure at a mid-sized American University: DON'T GO TO GRAD SCHOOL FOR A PH.D. IN HUMANITIES OR SOCIAL SCIENCE UNLESS YOU ARE INDEPENDENTLY WEALTHY, YOU DO NOT NEED A JOB AFTER SCHOOL, AND YOU ARE PASSIONATE ABOUT THE FIELD OF STUDY. Otherwise you're setting yourself up for an incredibly stressful life with limited earning potential and even less job mobility.
Sorry to piss in your cheerios, but you need to know what you're signing on for. If you're aware of this and you still want to do it, at least that's an informed choice, you know?