So, I get all my greatest ideas (most have not been shared) when I am bored. I am at school, and not even my teachers are into what they are explaining, or I have spare time to do something, and I take out a piece of paper and write down my ideas. My Project MAGIC idea came from that, as well as SpyCraft, DiasasterCraft, From The Ground Up, and other adventure map series that I have not released yet.
So, here are the BEST ways to get inspired:

1) Look at other people's work.
-You will strive to be better then them, or just as good, when making ANYTHING, not just maps.
2) Come up with a backstory
- You will feel more invested in the project, this mostly applies for maps and skins, and want to finish
what you had done.
3) Never Give Up.
- This is the inspirational crap that everyone tells you. cliche, but true. you can't complete what
you never finish (Ya don't say!).
4) Come up with things you can do to make your work interesting.
5) Have routine, your subconscious will do more thinking when you are doing your mind-numbing routine.