Its just a matter of fact that as we get older "things change". Its doesnt really matter if you are 22-45 or 70, you need to have a good understanding of your abilities as a physical human being. Not just for SD purposes but as a general purpose of getting though life. Understanding your abilities and limitations as we age is just a life experience process that is closer to instinctual than anything else- specific ages dont matter all that much.
Life is a web woven by necessity and chance...