The universe is in constant movement as are our cells. Nothing is static. Billions of neurons are sending currents through us all of the time. Energy needs to flow. If hatha yoga is not something you want to partake in, there are many other options; take an exercise class, buy a DVD, or just turn on the music and let your body rock!  Maybe become involved in a sport like ball or swimming. I took private belly dancing classes many years ago and I loved the muscle tone and strength I felt. I became in touch with my natural sexuality and enjoyed looking at my reflection.  We are never to old to move and let our natural rhythms flow. I have had two femoral artery bypasses and a broken right knee in the past seven years but I intend to start taking classes again. My heart will benefit!