When you're strength training, whether you're using dumbbells, resistance bands, or machines, most of your mind is probably focused on the muscles getting worked. That's great, but you don't want to forget about proper form, and part of that means thinking about your shoulders. You want to be sure to relax them and elongate your neck.
A trick I do to help me remember to relax my shoulders is to scrunch them all the way up towards my ears on an inhale, and then I release them down on an exhale. Then while keeping my spine straight, I draw my shoulder blades ever so slightly towards one another, so I can feel an opening in my chest. Give it a try the next time you're strength training, because releasing tension in your shoulders will help to prevent neck and shoulder pain after your workout.