Some signs of aging are all too obvious when you look into the mirror...you've probably got a few more lines than you did when you were 25, and your hair may have changed from brunette to silver over the years. But how much attention are you giving to what's going on inside your body? Although there may not be any outward signs, if you are a woman who has reached menopause, you're most likely losing bone density every single year. This thinning and weakening of bone is called osteoporosis, and unlike many other age-related conditions, you can have it and not even know it. The first indication that something is wrong could be a fractured hip or vertebrae, which could easily spell a permanent end to your busy, active lifestyle.