Treat Music as a Game
Another take on this is to play creative games. Like a drama-class warm-up, creative games exercise your lateral thinking skills without the pressure of 'getting something done'. If you manage to achieve something during the game, that's brilliant. If not, it was just a game designed to get you warmed up for the session.
Use novelty to keep the task fun. Write a guitar riff on a bass, make a reverb patch out of a delay, or drum without your most dominant limb. For DJs and producers, mix a slow burner into a club banger, build an entire song from a saw wave, or sequence an oscillating effect. Follow your joy and your brain will respond with creative solutions.