After some thought, here is a cogent answer: The difference between a pitch for shoes for old people vs. young people is comfort vs. style, function vs. appearance. So, an ad campaign could focus on this difference, by showing the awkwardness of, say, high heels, vs. the balance of, say, a crossing guard’s shoes. A slogan could be “My life is finally making sense.” Stress the “wisdom” or “good sense” of grown-ups vs. the frivolity and impulsiveness of youth. “Shoes are the foundation of a life well lived.” In terms of the design, stress the solidity and firmness and practicality of shoes as items of clothing (they could be called “Sensible Shoes for Grown-ups”). In terms of appearance, you might want to try for a vintage look (19th and early 20th centuries); also, keep in mind the limited mobility and dexterity of maturity, so maybe Velcro? You could have a nostalgic tone to the advertising, and maybe give away button-hooks.