I bought a piece of 1.5 inch stiff foam to try to fix a sag in a bed. It didn't work but having that thick piece of solid foam around has been a life saver.
Need something flat to put a laptop on? Throw it on the foam. Going to be doing something that requires you to be on your knees for a while? Get the foam!
It went from stupid purchase to something I'd gladly replace if it broke.
I wrote a huge reply about Garmin watches and felt like a shill, too, but it got lost. I will just add on to your reply to say Garmin watches rock. They cost more upfront but it feels like I'm wearing a scientific instrument vs a watch, for all the info it gives. Battery life is amazing, as you said.