Lunge + Reach. For the full effect, tuck your pelvis under to feel the stretch insanely through hip flexor, obliques, and psoas. s
Clam shells. 3 for 10 reps each side. Strengthening the glutes relieves lower back pain by stabilizing the pelvis and preventing the lower back to doing the heavy lifting.
Similar to a Cobra Pose, use your arms to press up your torso. Repeat 3 times, hold for 3-5 seconds.