Causes of shoulder pain from activities of daily living are an almost 100% sure sign that you are treating your body badly. Why? Because it means that tasks like sitting at a desk and reading, painting a wall or gardening are triggering pain in your shoulder.
Actually those tasks itself are not really demanding, but if they become, it is a sign that you got too weak or imbalanced to execute them.
I could say to you: “Yes, sitting at a desk for hours or painting a wall is demanding”. But in my opinion it is not. It just becomes demanding to our body if we do not take care of ourselves and forget about the physical needs of our muscles. They want to get used.
Fact is, that if you have a troubling shoulder, there is a big chance that the pain is initiated by trigger points. It is also a fact that those trigger points can be caused from sitting at your desk four hours every day, which in turn means that this activity was too much for you.
But it is also known – and I have experienced that with a lot of my friends – that trigger points are more common in physically inactive people. When you start to train your muscles properly and additionally do some counteractions like stretching and mobility training, they will get stronger. Eventually they also get more resistant to stress. Then, sitting at a desk for hours suddenly becomes easy and not tiring at all.
It is really how much work our muscles can bear. So, if you experience shoulder pain from some normal daily activities, I suggest that you are currently just a little too weak to execute them properly. It is time to get in a better shape again.
Not the daily activities itself cause the problem but the prior inactivity. Inactivity is one the most common causes of shoulder pain. Being sedentary often involves sitting at a desk for hours. When sitting at a desk, you might be in a round shouldered position for longer periods of time. This leaves your chest and front of shoulder muscles in a shortened position while constantly elongating the muscles at the back of your shoulder.
This chronic shortening and elongating of muscles causes too much tension and eventually tender and trigger points in them. I have already discussed and explained the round shouldered position in more detail here. In this article you will also find an explanation how accidents can be causes of shoulder pain, even after damaged structures have already healed.
What to do now? I recommend to get started with some massage and relaxation exercises for your shoulder. For learning which muscles to massage, visit the "symptoms of shoulder pain section". As soon as your pain eases, I recommend starting out very slowly with some strength training.