I take a nap or simply walk away from a few minutes. It also helps me to play VR games for a couple of minutes just to refresh my memory and boost creativity. I find it effective for me, even though I only get to do it for about 20 minutes or less, depending on how busy my day is.

Sleep enough.

I dont to this often, but my best business ideas came when doing small doses of LSD

Write down a problem, take a nap, wake up with the answer.