Do you believe that women like myself, at the age of 43, can firm up just as much as girls at 20 or 30 years of age? I don't need to lose weight, although I would like to believe that by sticking to proper training and diet, I will be able to tone and tighten my thigh and buttock areas.
Honestly, it may be a little harder if you're starting at 40 or 50 for the first time ever. People who have been working out their entire lives have a "head start" and that's a decided advantage.
However, I have seen some absolutely amazing success stories from men and women in their 40, 50's, 60's, 70's and even beyond! Nearly every body building show these days has a masters division for age categories starting at 35 years old, and going as high as "grand masters" for ages 60 years and up. I know for a fact that many of these masters champions didn't even start working out until their 40's or 50's. Most people have no desire to become bodybuilders, but this example just goes to show that it can be done!
In fact, you will get stronger, leaner, healthier and see cosmetic improvements from training, no matter how old you are.
In his Boston research clinic, Dr. William Evans of Tufts University discovered that the muscles of older people are just as responsive to weight training as those of younger people. In his Book, "Biomarkers: the 10 keys to prolonging vitality," Dr. Evans wrote:
"A 12-week program of strength training using 60 and 70 year old men resulted not only in substantial increases in strength (their lifting ability went from 44 lbs. to 85 lbs.), but also in muscles that were larger and leaner with less fat in and around them. An 8-week study of 87 to 96 year old women confined to a nursing home showed that resistance exercise tripled their muscles strength and increased their size by 10 percent."
My suggestion is to avoid comparing yourself to 20 year olds, but don't set mental limitations on yourself either. You can and will see dramatic improvements in your body from working out regularly; simply make your goal to get better than yourself, not better than someone else half your age.