Most school programs don't build in much information about how to navigate this, so I thought I'd share the most recent version of what I tell my students when they come to the place where the pressure is greater than the joy.
The wonderful is that you can completely immerse yourself in the work that matters most to you, develop your ability to make that work more authentic and of greater quality, and build a community of people who care about pursuing their craft.
The terrible thing is that suddenly this creative play that has always been a way of escaping the drudgery of life is now the drudgery. It is the stuff you must do, not just the stuff you choose to do. In school, it's the stuff you must do for grades. In career, it's the stuff you must do so you can eat and keep the lights on.
One of the hardest things about going to school for writing or any art is that for the first time you must find the balance between these two.
Sometimes you're going to turn in work that isn't your best. In a deadline-driven world, that will always be true. But one of the best ways to get your work closer to your best is to find a way to have fun with it, even when it's required.
Art is rebellious and personal and universal and wondrous and scary all at once. When you're finding yourself under enough pressure that it stops being fun, notice, give that a nod, and look for ways that you may be able to let some of the adventure back in. I recommend artist's dates (see Julia Cameron's The Artist's Way) and rebellion. By rebellion, I don't mean jumping in a tie fighter or heading off to the Hunger Games. I mean look for something else that you can safely put off in order to have a little fun, something that is not your writing. Maybe it's laundry day. Take yourself to a coffee shop and write instead. Live with the pressure of not having clean underwear for a couple days instead of the pressure of not having freedom to write spontaneously, when you want to.
Or look for an idea in the world that drives you mad because people seem to think this is how reality works, but it's not - write a bit that rebels against their misconception. This can be satire, fiction, whatever. Just something that gives you that subversive satisfaction that you're doing something you're not supposed to.
Of course, that has to be balanced, too, because walking around in dirty clothes for too long has its own bad consequences, but you see what I mean.
Look for ways to keep writing an adventure, or you'll grow to hate it. It gets easier to maintain the balance the more practice you have, but we all need to refresh our sense of wonder now and then.