"I started going to the gym three days per week!" To hear someone that has done little to no activity for themselves for years, it's hard not to just be excited at that moment. When you're dealing with someone who spends a majority of their day either sitting in their car, sitting in front of a computer, and sitting on their couch at home actually engage in physical activity... you want to pat them on the back and just be happy for their accomplishment.

You also want them to be successful. I want them to feel better, to have better posture, and end their back pain. I don't want them to be discouraged because their posture seems worse and their back hurts more. That will only lead to them discontinuing all activities again. If I can direct some of what they do at the gym, they may just see the results they're after and keep it up!

If you are going to the gym and using the cardio equipment, you'll want to avoid things that going to make them worse. The treadmill is okay if you stand straight while you're doing it. The recumbent bike and other stationary bikes seem to keep the person sitting with bad posture or slouching over the handlebars. The stair-steppers also seem to have a high incidence of people leaning on the machine. If you're going to hunch over all day and then hunch over on the machine, you're not going to help your situation.

I usually recommend the elliptical machine, because it almost forces you to stand up straight, requires some coordination, and has no impact on your joints while you're doing it. Great for people looking to make a healthy change.

As far as the exercises you choose, the machines, and the weights, just remember that you're trying to counter all the other daily activities that you perform. The weakest area that will help the most is to strengthen your back! Doing bench presses and abs will only further hunch you over unless you balance it with likely twice as much activity to your back.

You can't keep working the front of your body and ignoring the back and think that your posture will improve. You can't keep your back muscles long and weak and think that your back pain will end. Working the muscles that you can see easily in the mirror may make you feel a little better when you start to see some tone in your muscles. Unless your working your back muscles, that "tone" may be telling you that you're on your way to more back pain.

Perform exercises that help you keep good posture and you'll maximize your efforts.