Fellow speaker,
Improv professional Izzy Gesell suggests a simple way to build creativity, humor, and comedy is to play the "yes and" game with someone. You suggest something to someone and they reply "yes and" to your idea. They accept your idea and build on that idea. Then you reply "yes and". Practicing the "yes and" game will open you up to new ideas you might have been closed to before.
Openly,
Tim