Jill Tucker, RN says:

“As we live longer, it’s more important to maintain fitness in middle age in order to live well in our later years. Even if you have never exercised, try starting with a simple routine like vigorous walking or stair climbing. As the study notes, a person making a move out of the ‘least fit’ category to the next healthiest category will notice potential major health benefits.”
The Benefits of Middle-Age Fitness

Well.blogs.nytimes.com  September 5, 2012