I let the intrusive thoughts win and hung my ceiling nightlight thing from the inside shower curtain and shower with the lights off. I find it more calming--not that I found found showers not relaxing before but feels like I'm shutting out the outside world more and that I find more relaxing.
I also have some of those bone conducting headphones that are waterproof so I listen to podcasts while I shower as well.
I love them. The inside of my mouth, not so much.