Ideas are kind of like stars. No, bear with me.
Stars need time to form from the gas and dust of the interstellar medium. You have to leave that delicate substrate alone for it to undergo gravitational collapse. If something big happens nearby - a quasar, a supernova - the gas is blown away, scattered, and no star forms.
Like a stellar nursery, my brain matter sometimes needs to be left inert so that it can generate new ideas. I have to turn off the podcast or the music and starve my brain of stimulation . Then, I guess it has to generate something to amuse itself. And it works! A lot of my ideas come in those moments when I'm dead bored, when I'm out of podcasts on the way to uni and my brain is begging me to feed it something. If I do, no ideas form, just like a quasar quenching the interstellar medium. But if I leave that lump of grey matter to its own devices, it reluctantly churns out the occasional star.