It starts with a twinge when you over do something and you figure it's probably nothing. Gradually, it occurs more often, but you accept it since you've experienced it before. You think it's "just" Aging. Maybe yes, maybe no.

I had a yoga teacher who explained how we lose our balance and strength as we age. It starts with a loss of core strength. Those abdominal and pelvic muscles that keep our back strong weaken with lack of use (you sit at a desk more and don't play as much on the weekend) and, if you are female, childbirth. So, the ribcage collapses forward slightly and excentuates the curve in your lower back, weakening it further. It also pulls out the curve in your thoracic spine, causing your neck to hyperextend so you can see where you are going as you walk. This all pulls you out of balance over your pelvis, so you are fighting falling forward with each step, so gradually that you don't notice it. Until you think about the little old lady with the walker- that's what you're working toward.

If this isn't what you are designing to be, then rethink your exercise regime and your diet. It's all related. If you don't have enough minerals in your diet, as your bones demineralize you will start a similar stoop from lack of bone strength in your spine.

All issues of aging start like this. A small aggravation which we ignore until it is too big to be ignored. Can't walk as far or as fast as when you were 20? That problem started at 35, not 55. If you don't take care of what you have now, you won't have it long.