Lifetime Fitness offers free classes with membership. The dues are high but it is well worth it to me. I personally take the water arobics at the Plano and Allen locations and I really enjoy them. The class is suprisingly a pretty good workout. I have also heard Cooper Arobic Center offers classes but don't know that for sure. Plano parks and Rec. also offers classes. Frisco may also offer a class through their parks and rec. Hope your back is feeling better soon.