You may have to live with neck and shoulder pain and aspirin. Almost every book I have read on touring mentioned it. On all my tours I've had it. There are various sports stretches which target the muscles and bones in those areas. They can relieve tension and stress. Many complained of pain in the lower back-spinal area, most particularly when climbing hills. Every form of transportation has its tradeoffs. Every form of refuge has its price.In addition to getting the fit right, I have to do a whole series of stretches several times a week. They seem to help a lot for the activities I do. biking seems to be one of the hardest on the body. I have to stretch for achilles, hamstring, lower back, and neck problems. I seem to have reached the place where, with the fit right and the stretching, and some work with light weights, things are good. I'm also 61 and was touring and riding a lot 30 years ago with very few of these concern.
Another thing that really helps is to not get too obsessed with one sport--I mix it up and in that way give the critical spots a break. There are, of course, some books on staying fit and healthy for riding. Do your research and keep riding!