If I could improve only one aspect of my day-to-day biomechanics, it would be how my lower-back tends to sit on my hips: This has always been this way despite working bridges and hamstring flexibility, though admittedly I haven't really focused with any sort of rigour on fixing the issue as progress has always been so frustratingly elusive. In the image above, this is the position my back naturally curves into – and I can't comfortable sit this way without support for long. The same issue occurs when otherwise seated without back support, such as cross-legged. Moreover, even if I do have back support, such as in a chair, the force pushing from my lower back against the support – as you could imagine in how my lower-back protrudes backward over my hips – tends to push my butt away from the back support, creating an increasingly slouched position the longer I'm seated. The result is that, in a world where sitting is so common, I'm often not comfortable – hence why this would be an aspect of my biomechanics I'd first choose to improve over any other. Here's me doing some hamstring stretches to show how the lower-back/hip issue persists despite above average hamstring flexibility: Here are some questions I have: -What is the likely issue with my biomechanics (please let me know if more info is needed) that's causing this? -Given that that's the issue, can I improve it – and to what extent can I improve it? -What specific exercises can I do to bring about this improvement? Thanks!