I pretty much agree with everything in Anthony’s post about The Positive Side of Limits. In short: certain types of limits can help fuel creativity.
For me, it’s true that if I’m not given any parameters it’s harder to create. I think that’s why I like themed anthology calls, even if I’m not really a short story writer. There’s a nugget of an idea to start with, and if you know the subject, then you also know where the soft edges of the idea are. The edges are what I like to play with if I can find them. That’s where you can bring something new to a genre or a trope. Also, anthology calls have a submission deadline, and well, if they didn’t I probably wouldn’t start typing.
I often create self-imposed limits just to have somewhere to start on a story. Sometimes they are time limits, or a certain sets of ideas (like the short story exercises we did ages ago here). More often than not, when you start deep diving into one idea, oceans open up around you. There’s always more to it than you think.
Word count limits can also be helpful. Seriously. When it comes to novels, having an idea about standard word counts, or the rough word counts of books I’ve read, helps me figure out where I am in the story I’m writing and if the pacing is right.
And of course, whenever someone imposes a limit like telling me I can’t do something because I’m not capable, or because of something dumb like I’m a girl, then you know what that means… That just gives me extra motivation to try.