Relaxed stretch for back?

I'm trying to improve my bridge at the moment. My shoulder, wrist and back are quite stiff so I can't hold a bridge very long. I did try the wall walking which works good, but it's becoming quite tiresome after few sets. So I was thinking if there is anyway to stretch my back in a relaxed position? Or is that counterproductive if I do it relaxed?

Seal position, yoga cobra position with arms in support. Hanging from a bar or rings and doing small swings in your hips.

Try working the bridge with your feet elevated somewhat so you can work on opening the shoulder angle rather than bending at your back to support yourselves.

Thanks, that's excellent tips. You have always been really helpful Blairbob.

I try to be and as mod figure that's sort of my job.