Top Hollywood stylist and busy working mom Karla Welch knows her sartorial stuff, whether she’s dressing Lorde for a music video (a vintage disco dress and Adidas Sambas) or Oprah for a cover shoot (Gucci moto jacket). We quizzed her—hard—about athleisure while she walked us through the collection at Six:02, a go-to boutique for chic workout gear. And she rewarded us with brilliant advice on how to wear athleisure while still looking chic and age-appropriate.