Claire McAdams loves to snow ski. But when she hit her 30s, something felt different. She found she had to stop two or three times on the longer runs of the day. Her stamina wasn’t what it used to be. “I needed to find something that would keep me in shape,” she said. “But I wasn’t into running and I’m not really a yoga person.” When her massage therapist suggested Pilates, she decided to give it a try. Today, more than seven years later, 40-year-old McAdams says she can ski all day without stopping — something she attributes to Pilates. …