My problem is defining when middle age ends and old begins. My dad was old at age 40. He abused his body with alcohol and cigarettes and was dead at age 70. My father-in-law doesn't drink or smoke, is 76 and this man is a firecracker, going off everywhere. The man can't sit still for a second and is always on the go. I'm 56 and 5' 9" (I know, a manlet), don't drink alcohol or smoke, I exercise regularly and got to my target weight of 145 lbs. During my physical last month my blood pressure was 110 over 69, and all of my blood work came back great. My wife and I did a ~10 mile hike at a local state park last weekend, and I felt great and wasn't really even tired the next day.
So I guess what I'm saying is that maybe defining whether people are middle aged or old should be based on their physical well being as well as their mental attitude.