The Standing Row exercise strengthens shoulder muscles including the trapezius. It can be done with or without weights. The standing row exercise also will strengthen your biceps and back postural muscles.

Stand in your golf posture, arms extended out in front of you, holding light hand weights.
Slowly squeeze your shoulder blades together bringing your elbows up to your back.
Drop arms down to start position and repeat motion.
Do 8 to 10 repetitions.