I have a professional messenger bag (chrome mini metro messenger) I have been carrying for about 2 months. The bag weighs around 3 lbs and I generally carry about 4 lbs of stuff in it. Biketools, phone charger, gloves etc. Its less than 8 lbs and I still get shoulder pain.
I am 190lbs and 5'10
Am wondering if there is something I am doing wrong - I see a lot of messengers in the city with huge bags and always wonder if they have shoulder pain from carrying bags on one side for years.
Below the actual bag although i have it higher up without using the side strap.