NEW YORK—Calling the cheery new mindset the must-have accessory of the season, top designers from Dior, Versace, Chanel, and dozens of other premier fashion houses agreed this week that this spring’s hottest style trend is an upbeat attitude matched with effortless enthusiasm and a positive inner glow that radiates from within. “Right now, the fashion world’s most influential trendsetters are all sporting a bubbly demeanor that’s equal parts chirpy optimism and buoyant confidence—it’s a vivacious and good-natured temperament that can be seen on every runway from London to Paris to Milan,” said Vogue editor Anna Wintour, noting that the spunky, can-do positivity was already beginning to dominate billboards and magazine spreads, and that pleasant, worry-free countenances and beaming, self-assured smiles could be seen in every haute couture atelier, boutique fashion shop, and high-end designer store along Seventh Avenue. “Forget about shoes, forget about clothes, forget about makeup; the only thing you want to be seen with this season is a joyful, outgoing posture and a big toothy grin that says, ‘I’m fully content with who I am and I want to bring heartfelt warmth and joy to other people.’ I for one won’t go anywhere right now without a cheerful twinkle in my eye and a skip in my step. Nothing could be more ‘in.’” Though Wintour predicted that a sunny attitude would remain in style through the end of the spring season, she noted that she was already predicting a return to traditional masked insecurity and self-destructive narcissism for fall.