I find being creative in adult life kind of difficult.
I have vague recollections of school assignments composing 10 minute operas, writing Gothic short stories and designing cushions and key fobs with relative ease. Even at university I found my song writing and orchestration assignments - even writing the script for my final recital - far easier than I find attempting the smallest creative task now.
For a while (and by 'a while' I mean 'for the past year and a bit') I have thought it would be great to write a 1 person show as a long term project to develop and maybe, one day, perform. But for the life of me I haven't been able to come up with an idea, or at least an idea with enough sticking power to last more than a couple of minutes in my brain.
I've also been writing/attempting to write poetry as practice for when I finally (touch wood) think of an idea for my solo show of theatrical wonderment. And sometimes I get something down in 5 minutes.
But most of the time I can't write anything!
I figure there are 2 reasons for this:
Creating things at a younger age is just easier
Having rules/criteria to follow and deadlines to meet helps you to create
The "More Creative When You're Younger" thing is purely based on my own experience, although I think that it is generally true as you tend to be less self-conscious about what you create at that age. This is partly because self-consciousness is something you learn, some earlier than others.
But also because the things you create as a kid tend to have less emotional attachment. The opera, Gothic story, cushion and key fob weren't even in aid of gaining an official qualification; I just did them because we had to. And when you create stuff outside of school it's for fun; fun is less pressure. My hypothetical play, on the other had, at some point would be performed in front of a paying audience and potentially be a fairly important episode in my acting career. Which I know I shouldn't be thinking about, but I do, and it kind of sucks the fun out of making a blank canvas less blank.
As for "The Rules", I think that boundaries help narrow down your options and, therefore, help you decide what the frick you're going to do.
Take my hypothetical show, for example. I could base it on a character in a book, a film, a TV show or another play. I could base it on myth or legend, on the life of someone from history or on my own life. Or I could make up a completely original idea. And that idea could be about racism, or feminism, or growing up, or community, or society, or anarchy. And be set now, or in the past, or the future, in England, or China, or Mars...
It's hard to chose from all the things!
But when your lecturer says "Write a children's song about going to a magical place to the tune of the Harry Potter Theme", you know exactly what you have to do and you can just go and do it. And you can't second guess the idea and be like, "This children's song is dumb. I'm going to write a song about world famine to the tune of Poker Face!" Because you HAVE to do it and so you make it work.
Unfortunately I don't know what the solution is. Even when you place restrictions on yourself you can second guess the rules you make.
Maybe someone else needs to make the rules.