I didn't know where else to put this, so if it's in the wrong spot, sorry.
My lower back has reasonable flexibility, so that's not the issue. The problem is that I think my abs are significantly stronger than my lower back (in all honesty, I train my abs much more directly and more frequently) and I think it has pulled my stomach forward, therein putting a lot of (hopefully unnecessary) pressure on my lower back and effectively ruining my posture. It's a constant discomfort, though it's alleviated by laying or sitting down.
Could this be the case? I plan on using the book to help strengthen my lower back and if anyone else has any suggestions, I'm certainly open to trying them out.