Recently I have been trying to start an exercise regime because my wife and I are wanting to start trying for a baby. I've led a semi-active life. My job requires me to walk a lot, but other than this, I do very little exercising. I run on the treadmill 3 days a week, a half hour each time. I range from 3.0 mph to 4.0 mph. I do not tire easily on the treadmill, but my problems come the next few days. When I wake up (or on the evening of the first off-day), I have pain along my spine. It hurts to take a deep breath. I also have other pains, mainly throughout my back and sides. I once tried the treadmill's incline and the next day my lower right side/back hurt and now hurts on and off. I've been doing the treadmill for a little over a month and was wondering what I need to do in order to not be in such pain each time. I want to add strength training but I'm afraid of overdoing it. I feel like I have very brittle muscles, as it seems I'm doing the bare minimum. I can't imagine scaling it back. What do I need to do in order to make my workouts hurt less and be more successful?