You should have a concept to work from before opening your modeling program. That way you don't have to think! Or, maybe take a little time off? Not modeling for a week isn't a huge deal. Go have some fun and find your inspiration.
I have run into the same problem for a while now and I think I can narrow the problem down to a simple thing right now: I'm not an artist, I'm an 'engineer'. Of course not literlly, but I noticed from other peoples work that they do amazing work on the fly and I suddenly realised that everytime I try work on something I…