The Good Ol' Glute Bridge!
With all my lower back issues starting to subside, glute bridges have been a great addition to both my morning and nightly stretches.
A glute bridge is one of the simplest things that you can do to get a nice full lower body stretch and it will totally wake you up in the morning and even more so: it will give you immense back pain relief!
(source - shape.com)
My favorite way to do glute bridges is to do them exactly as seen in this gif.
I do about 12-20 reps in a 4 set variation.
I'll do that in the morning and then repeat it before going to bed at night.
When done properly, you can feel a complete stretch throughout the glutes, through the hamstrings and even in the calves!
Try it out and tell me if it helps you in any way!