I have a homework assignment for you today. Check in with yourself every hour and ask yourself, "Where are my shoulders?"
If you are like most of us, the answer will usually be that your shoulders are shrugged up almost into your ears most of the day. Your shoulders start rounding forward, your chin pushes out further, and next thing you know you are looking like the caveman on the evolution chart.
At the end of the day, are you exhausted and your neck and upper back are killing you? Holding our big old head up is no easy task! According to the kid on Jerry Maguire, the human head weighs 8 pounds. Also, dogs and bees can smell fear.
Holding 8-10 pounds out of position like that really wears on you when done for several hours. So check in with yourself. Relax your shoulders, sit up straight, engage your core muscles, and pull your shoulders back. A tip I try to remember is imagining that a string is tied to the top of my head and it is pulling me straight up almost lifting me out of the chair.
You will find that you have more energy, are in less pain, and feel like you can take on the day with a little bit extra oomph. You can also apply the "Where are my shoulder question?", when you do exercises like rowing and pressing movements. Avoid shrugging your shoulders during those exercises and you will be make them more effective and decrease your chances of getting hurt.
Hope this helps! If you ever have something you are struggling with, please pass it on and I will help however I can.