Middle age is when your broad mind and narrow waist begin to change places.

E. Joseph Cossman was best known as an American entrepreneur and motivational lecturer whose sayings circulated widely in mid‑20th‑century business and self-improvement contexts (often in quotation collections, newspaper fillers, and after-dinner speaking material). This line belongs to a long tradition of humorous definitions of “middle age” used in popular talks and syndicated quip columns: it riffs on the idea that, as people reach midlife, they may become more intellectually expansive (“broad-minded”) while also gaining weight (“narrow waist” disappearing). The joke’s setting is thus less a single documented occasion than the era’s culture of aphorisms and light social commentary about aging.

The joke hinges on a reversal: in youth one may have a “narrow waist” and a “broad mind,” but in middle age the mind is imagined to narrow (becoming less open, more fixed in habits) while the waist broadens (weight gain). The quip compresses two common anxieties about aging—physical change and intellectual or emotional rigidity—into a single image of “changing places.” Its humor depends on exaggeration and stereotype, but it also carries a mild admonition: stay mentally flexible and attend to health, or time will quietly invert the qualities you once prized.