Sex at 70 is surprisingly satisfying

Good news for the sexy septuagenarians: Researchers at Germany's University of Rostock have found that "regular sex" increases not just physical agility but also mental acuity in the over 70 set.

A whopping 70 percent of 75-year-olds in the study reported being happy with their sex lives, up from 57 percent of 63-year-olds.

The name of the study? "Use It or Lose It."

How old are you—and are you happy with your sex life?