Try using old socks, fill with rice, tie off and nuke it till warm but not hot. You'll have to adjust the nuke time depending on what temperature you prefer. This makes a poor mans foot therapy. I've used massage oil to rub into your tired feet, then use the warm therapy, then put on regular socks. I wear socks ALL the time, mainly to keep from walking on the cold tile floor, the other reason is to keep my carpets cleaner for longer.