Love this article.

For those who workout, one thing to be wary of is if you feel MUCH younger than your biological age. I'm 70 and often feel like I'm about 30, but when I'm doing kettlebell squats or presses, my body is saying, "Um, Don, no way you're 30, be careful!"

I don't mean to NOT exercise but remember - your body may be just a wee bit older than you feel, and take care accordingly.