How do you come up with product ideas when you're in a mental rut?

You first figure out how to get out of the mental rut. Happened to me a few years back. I stopped trying to come up with anything creative and focused my attention on getting rid of the writer’s block. For me meditation helped as well as taking time of and doing things other than work. I researched causes off brain fog and over the counter supplements and ended by taking ashwagandha, fish oil and and some sleep supplements. I did nothing but worked on overcoming the rut I was in for about a month and eventually I got out of it and suddenly ideas flowed easily. It seemed ridiculous at the time to take time of, when I was behind on time, but turned out it that the month off saved me many months of crawling in circles. Disclaimer: I am not endorsing or recommending any supplements here, just sharing my personal experience. Supplements are very subjective and what worked for me might have the opposite effect on you.

You won't be able to come up with good ideas while in a rut. First deal with the rut.