To gently stretch the back and neck for upright posture try lying either on the floor or a foam roller and relaxing your low back as you lengthen the back of your neck away from your shoulders.
Start 1 minute and progress to 2-3 minutes. 1-2 times/day
Click HERE for full program.
Low Back Pain Home Program
Image from "Anatomy for Runners"
by Jay Dicharry
Three Form Drills to Decrease Impact