I never really used to bother with warming up before PE, because using a cloth and hot water just felt like a chore. Then I learned of the rice sock. Wow, I love it. So easy to use and feels good too, I sometimes even use it on my off days. It's also helpfull when socks go missing and you don't know what to do with the lone one, lol. Well, anyway, my question is: Do you have to change the rice in the sock at all, or can you keep using the same rice? Will it start to spoil or anything of the sort? I've been using the same rice for about two months.