Quotes are somehow like art, it's an opinion said within certain context. By thinking simple can be as expansive and complicated than one may think. Simple rather than neurotic, worried, overthinking, etc, etc. You can't get someone's thoughts and impose your own interpretation.
Same with age, some people grow mature, work hard, set examples, and some think of age as a mark, it doesn't mean you have to be bold, have gray hair or even be impaired following a standardized chronological table. Poetry, arts, proverbs and sayings are not meant to be literal. And literal was all you did above.
Think of a context, a time and place that you have not witnessed. It would be as if I'd tell to some artist that the ocean or whatever he or she's painting is not at all that color. You or anyone else don't have the power to impose your own ideas to others imho.