Workout Routines

I tend to think if anyone else my height did the same workouts and had the same calorie consumption as me, he would be 140 pounds. I’m 195. Why do some people just seem to maintain weight (even if it does revert to muscle, largely)?

I’ve never worked out before, so I need really simple and easy to do instructions. I have a really difficult time loosing weight because I have a thyroid problem, but I’m not going to let that stop me from trying.