I like to take showers in the dark with the door cracked open, or with a couple candles. It's warm, dark, comforting. A lot like being in the womb, I think?
You've probably experienced or heard that the shower is a fairly reliable place to have epiphanies or ah-ha moments. It's because you’re relaxed, feel safe, and it’s dimly lit. There isn't a lot of stuff to look at or think about — you're only responsible for getting clean, if even. Sensory stimulus is minimized, and so your your brain is freer to come up with ideas.
You need quiet to spark an idea, like how right before a match lights up, there's a barely perceptible space of quiet, and then ptschhh.
If you're leading a highly-stimulated, do-centric day, quiet time is hard to come by. I call it "Tinker Time": you can physically tinker and make something, or just daydream and tinker with ideas. Need more ideas? I invite you to build Tinker Time into your day by scheduling it on the calendar. If you don't make it do-able, you won't do it. :)