The way things were described to me was as follows - imagine that to "do your back in" takes a 100 different movements. Most days you'll do 70 and you'll be fine. Some days you'll do 80 and you'll feel a bit of soreness. Some days you'll do 90 and feel very tender. Then one day, you'll have done 99 things and then bend down to pick up that paperclip and ping, something goes wrong. Of course you blame your trouble on bending down to pick up that one paperclip, but it's really a culmination of the other 99 things aswell. These will include factors such as your height, general gait, posture and history.
Also imagine yourself lying on the floor and then get up. You've probably got up the same way for the last 30/ 40 years and there'll be many other actions you do in exactly the same way over the years so your body is bound to wear unevenly.
The body is very good at making small adjustments, to cater for uneven wear or muscle imbalance, but sometimes, at some points it can't cope. Which is when you typically get pain.
So don't expect quick results, after all you've had a lifetime of building up uneven wear and you need to address this. The good news is that if you stick at exercises which a physio would show you, you can pretty much eradicate it.
I mentioned above about seeing a sports physio. I first saw him and was about to have surgery on my back, but I wanted another opinion. At the time I couldn't walk and was transported to him lying in the back of the car. One leg was markedly smaller than the other due to muscle wastage. Anyway he reckoned I had three different pain areas, two of which were caused by my posture trying to accommodate the original seat of pain. After only a few sessions, I was mobile and never did have the surgery. That was over 20 years ago and I've been fine since, only having slight problems when I've been lazy and not done my exercises for a while - so to you and anyone else out there suffering with back pain, there is hope.