You don't necessarily have to be a student to intern, and there are other ways of sampling careers. Do volunteer work. Help a friend, whose work intrigues you, on the weekends. I know people who tried on a new career just by entering a contest.
If you're constantly preparing to enjoy your life later, you're not enjoying your life. A few years ago, my friend Matt left a very well paid job as a lawyer because he wanted to open a dive shop on a beach in Thailand.