I've struggled with how to store my ear pro while the line is cold taking training classes. I saw someone a long time ago wrap their ear pro around their thigh, and that looked cool af, so I tried that for a few years but it would always slide down my leg while walking.
I do have electronic ear pro, but for ventilation purposes I like to take it off during breaks. I found some polymer clip purpose-built for this application on Amazon but it's too small for my ear pro since I use a head wrap pad on it.