1Chronicles 4:10c "and keep me from harm so that I will be free from pain."
A couple of years ago, I threw my back out. I wasn't even doing anything strenuous. I was holding a baby - I put the baby down and stood up, and there it went. I'm not one who might be considered an "old" person - I don't have other health issues that would have brought this on - why in the world would my back go out? The pain was intense. I have never felt pain like that before - I was immobilized. It took about two weeks before I could get back up and actually walk around normally - but even then, I was cautious for fear of re-injuring my back.
Jabez asks God to keep him from harm and free from pain. Obviously, physical pain can be such that you are not useful - that you become a burden to those around you - no one wants that. However, I think Jabez was asking for more than just that.
During a time in my life when I was not walking with Christ, sin had gotten a stronghold and I found myself in a very dark place, alone and defeated. This type of 'harm' caused, not only an immobility in daily life - just getting through the day - it also stopped and hurt any work the Lord could've wanted me to do during that time.
Jabez is praying for those things - protection from physical harm and spiritual harm - because the pain that both cause can be debilitating. God wants us to be free from pain, all we have to do is ask - Jabez figured that out.