My sister gave me a microwave sheep heating pad from Maine Warmers. I have a lot wrong with my back and have arthritis among other things.
Using the sheep when I first get up has made a big difference in reducing stiffness and facilitating movement.  I also use it during the day. In addition to selling a great product, it is a pleasure doing business with the company. I highly recommend the sheep. And doing business with the nice people who work at Maine Warmers.