There's this thing, it's called Lower Cross Syndrome. Basically, tight muscles in the front of your body (especially those pesky psoas muscles) cross with weak muscles in...back. As in, your butt.
And it is a major culprit of back pain.
This article puts it really well:
This muscle imbalance creates joint dysfunction (ligammentous strain and increased pressure particularly at the L4-L5 and L5-S1 segments, the SI joint and the hip joint), joint pain (lower back, hip and knee) and specific postural changes (lower back, hip and knee), such as: anterior pelvic tilt, increased lumbar lordosis, lateral lumbar shift, external leg rotation and knee hyperextension. But it also can lead to changes in posture in other parts of the body, such as: increased thoracic kyphosis and increased in cervical lordosis.
Lower cross syndrome can show up in either of two ways:
Both lead to pain, unfortunately, and sitting for long stretches can cause or exacerbate the muscle imbalances.
So, what to do?
Stretch your front and strengthen your butt.
Bridge pose is a winner. Also, a very particular lunge - which we teach all the time - you can see it in this video which has a really great, short sequence you can do daily at home.
And lastly, you need to spend time with your hips and shoulders in a position that allows the muscles in the front of your body to reset. I strongly recommend that you lie over a bolster like so https://nutritiousmovement.com/snapping-psoas-hidden-tiger/ every day. If you don’t have a bolster, a rolled up yoga mat will do, even a foam roller will do at a pinch.
Also? I could not resist using this image because it made me laugh so much.