Read an excerpt from fashion influencer Lyn Slater’s book “How to be Old,” and learn how her sense of style has influenced the fashion world.

“Just because I’m in my 60s doesn’t mean I want to start dressing like an old man,” said Jonathan Rone, a shipping consultant from Oakland, Iowa. You might recognize this 61-year-old from ...

But I am now 53 years old, which is an age, historically speaking, when people are dead. And I still dress like a child. I do not dress more immaturely than the other 53-year-old men I know.