Sir Paul McCartney is so stressed about his legal battle with estranged wife Heather Mills, he has taken up yoga to help him through his difficult divorce. The former beatle, 64, has been taking private lessons in The Hamptons in New York State with the same master who teaches actor Alec Baldwin. And the BLACKBIRD star has become so hooked on the rejuvenating exercise, he is attending classes three times a week to keep his mind, body and spirit in shape. A friend says, "Paul is a very fit and active guy who likes to stay in shape and has been doing a bit of yoga to help his emotional and physical wellbeing. "The last few months have been incredibly difficult and he is aware of the need to look after himself. He finds yoga the perfect way to help him unwind and relax."