Good morning and HAPPY FABULOUS FRIDAY. When looking at posture from a structural point of view, several possibilities to one shoulder being broader than the other. Muscle contraction of Levaror Scapula muscle on the shorter shoulder side (right for you), is the muscle from neck toward right shoulder painful to the touch? If so, that contraction will elevate right shoulder, and the result is right shoulder looks shorter and less broad. How long you’ve had this might be indicative on whether or not it can be fixed. Do you work at a computer? If so, then working with mouse always with right hand can alter the musculature from right side of your neck, through shoulder down to wrist, hand, and fingers. Sleeping postures can also lead to unilateral (one side) muscle contraction. Your weight distribution may also be a factor, if a woman or man carries a purse or bag on one shoulder everyday, then over time the body adapts to the stimulus, and people commonly lean to the opposite side to keep purse from sliding off shoulder. How old are you? You mentioned that you’ve noticed it now that you’re working out; key is for workouts to be balanced. If not, workouts can perpetuate the imbalances by making stronger muscles stronger, and the weaker side muscles proportionalely weaker. Another possibility can be a scoliosis (lateral or sideways curve of the spine). Best advice I can offer you is to get a thorough structural exam by a chiropractor, to be sure you’re in balance, and that the stresses to your neck and shoulder are even, and a doctor who can help you learn how to manage your structure so you can live a long, healthy, balanced life.