Pain Free Babywearing!
I find babywearing nearly pain-free. I say nearly, because sometimes, there is pain. But good pain, not bad pain. By good pain, I mean the kind of pain you might feel after a workout. After all, babywearing does involve toting gradually larger amounts of weight on your upper body.
Some examples of good pain are sore thighs, tired tush, maybe even a bit of pain in the hip flexor. Noticing a pattern here? None of the pain is in the neck, back or shoulders.
A good baby carrier, properly worn, should never cause pain in the upper body. If you have pain, you are either doing something wrong, or it is not the baby carrier for you; keep looking! For example, slings, pouches and mei tais are all excellent baby carriers but they are not comfortable for me, due to either back issues or just the way my body is constructed. I only find wraps and soft structured baby carriers comfortable, so that is what I use.
Find what works for you. Don't be afraid to sell of what's not working well. You should not need to reach for a pain killer after babywearing. Perhaps a bit of stretching might be in order!