Ohhh I understand that 'feel like a waste' feeling, very well. It makes you feel as though your a liability. I feel this way quite often, so you are not alone there.
I understand your reluctance to take opiates. Reading your words, it does seems that medication provides significant improvement in quality of life. Walking and exercising is a long way from laying around feeling like a waste. It seems opiates provide improvement in your physical and emotional well being. As you know, all that stress that pain brings, has a terrible toll on your body and mind. Being in a state of pain is doing you harm.
You are very strong willed. Your avoidance of opiates proves it, you are very strong. You can control it, and not let it get control of you.
If you need to use them to live a quality of life you deserve, then promise yourself to stay in control. Let your Doctor know of your concerns re: addiction, if you haven't already, so that he/she can help keep on eye on things.
I've read many times on these forums of people who avoided medication for as long as possible, and then when they finally gave in, their life changed so much that they wish they had of started on the drugs sooner. I think that is why I didn't hesitate. That, and the fact I'm a complete chicken!
Anyways, I believe you are capable of enduring life without opiates. Not many could, myself included. I rely on them just to live a relatively normal life.
I admire your strength and commitment.