Your tight hips are causing your sciatica pain.
Why this matters:
If you don’t have enough hip flexion (aka pulling the knee up), that lost motion needs to be made up somewhere. So when you’re trying to sit, your back will round and flex in order to sit down. This is not great news if you have a herniated disc. In fact, bending forward can make the disc worse, further flaring up your sciatica pain.
Action steps:Floss your hips. Get into a lunge, and move your pelvis in a circle. It will allow your hips to sink deep into flexion, as well as external rotation which is a crucial part of hip mobility. I recommend 2 minutes per side. See what side feels tight. More often than not, it is the painful side that is giving you problems.