54-year-old Kim Gustafson didn’t plan on starting a new business when he retired to Vail, Colo. But after his arthritis and the rigors of skiing exacerbated an old knee injury, Gustafson became part of the growing trend of “senior entrepreneurship.” Five surgeries forced him to wear an unwieldy brace on the slopes — that’s when he had the idea for pliable tights that could support active people dealing with similar injuries. Rather than the restrictive brace, Gustafson’s prototype used bands of rigid fabric sewn into spandex and nylon tights to keep the knee naturally aligned.  He partnered with the biomechanical scientists at the Steadman Philippon Research Institute, a branch of the clinic where he got his treatment, and in two years founded a company called Opedix to produce the tights and bring them to market. Gustafson isn’t alone. According to the New York Times, 23% of new business owners are now aged 55 to 64, a nine-point increase since 1996. In other words, the golden years are getting a lot more golden.