Here is an article that reviews a few books about seniors and sex. The same things mentioned in the STI article as being responsible for the increasing rates of infections among seniors are also mentioned here as helps to having more sex. It also mentions that penetrative intercourse is only part of sex. One idea brought out in the article is to plan some time to cuddle and caress in the nude.
I remember Jay Leno telling a joke in his monologue, for you young people he was the host of the Tonight Show. He said senior citizens had found a new contraceptive, it's called nudity. Hopefully, as a society we are starting to realize there is more to a good sexual experience than the person being hot looking. That may be a starting point when younger but even young people need to touch to build the excitement to the point of orgasm. If it is happening before touch for men, it is considered a problem called premature ejaculation. I'm finding a good erotic story will help get my wife in the mood. It always has but is more important now. I talk about the story and she is more receptive to my touches and caresses.
Edit: I have looked at the picture that shows. I'm sure those to people are in their 70's or at least near 70. This is what my grandparents looked like at 60. I think I now understand why some people are surprised to find out my age. Most just say I look younger but at least one was brave enough to tell me how much younger when she said I looked 10 years younger than I actually am.