I specialize in exercise for women because there is a difference in the needs for men and women.  Men typically want to get bigger muscles, while women want to tone up and trim down.  Men typically lift heavy weights, while women shy away from weights for fear of “bulking up”.  At one time in my life I was really into natural body building.  I have a naturally muscular build, so with effort I can get big muscles..but I also learned that I can make my muscles long and defined.  It’s true that your body can change with the exercises you do.  For that reason I have found that doing a combo of light weights, kickboxing, and yoga plus good healthy eating habits has given me and many of the women I work with amazing results.  As far as getting big muscles…most women won’t get them unless they work really hard at it, and have a mesomorph build (or a naturally muscular body).  My advice is to try a variety of exercises over a 3 month period of time and see how your body changes by the type of exercise you do.