Four months ago I started taking exercise classes. After the first few classes I started to realize that I shouldn't be afraid of my neck, upper back and low back getting worse from exercise. But then several months into going to class I was stretching my leg during my class and the next day I squatted down and felt pain in my hamstring. The pain scared and worried me so bad I stopped going to exercise class for 3 months. Should I be pain free before I exercise? I was trying to exercise even though I have pain in my back. I haven't gone to an exercise class for 3 months. Could this hamstring pain be TMS? I'm upset that this new pain has stopped me from making progress in my recovery. A few weeks ago I started run on a treadmill 4 times a week to try and get back the courage to completely get back into exercising.