I should begin by making my own perspective clear. I've been in my program for 4 years now, and still love it. By and large my friends are also in grad programs, though not exclusively, I know a lot of good, smart friends who don't know what they really want to do in a long-term sense, and I have two siblings who never went to college. The short answer is that I don't know, and I think the above posts do a good job of making some recommendations, which I almost whole-heartedly echo. I have no practical post-PhD experience. And there are a lot of bad reasons I've seen people get disenchanted with the process, though I want to stress that at some level, going may have been smart for some of these friends: it made them quickly decide what they actually wanted to do. And that's my little spiel here: you have to know the details of what you like, and build your decisions around them.
For me, I had three years off working an increasingly frustrating arts admin job and a filler year at a music publisher. I quickly discovered that I missed using the part of my brain that dealt above the practical side, that I hated budgets and loved the promotional aspects, in short, the aspects that allowed me to indulge complex arguments and the music itself, and where I failed was the practicality angle, being decisive about things I wanted to treat with more nuance. I also missed the general atmosphere of school, and realized that it was that kick that propelled me to work (this is not to say I was lazy in my work, but that the effort was increasingly noticeable). And so thanks to my years off, I vowed to enter into grad school only focusing on the parts I loved: the discussions, the self-propelled knowledge, the music itself, and the camaraderie. The parts I found more tedious (testing, politics), I've only applied myself as much as was necessary, and once done, let that go. Teaching, once I tried it, confirmed that I loved doing it, but that was a big big question mark.
My flight is boarding, but here's to enjoying not only what you do, but learning what you enjoy and how to enjoy them even more!