>>512030164

Open book stretch, look it up
Also lunges to stretch hip flexors, look it up
U can also lie face down with ur hands to the side palms like youre about to do a pushup, then squeeze your shoulder blades together, and curl your head upwards and the your upper spine upwards, like a turtle bobblehead. hold it there for a while then curl back down.

Also, do a ton of read delts,
face pulls, pullups and back exercises at
the gym (with good posture during them being paramount)