By Kate Hogan
Updated March 16, 2012 08:30 PM

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Monday marks the start of National Wellness Week, an initiative aimed at inspiring Americans to take charge of their health. To celebrate, more than 500 spas, gyms, yoga and Pilates studios are offering services for half price or a flat rate of $50 from March 19-25. Visit one of Jessica Alba‘s favorite haunts, like Vida Emanuel in Beverly Hills; loosen knots like Josh Duhamel at Massage Garage in Culver City; or sit back and relax like Sigourney Weaver and Lance Armstrong at The Spa at Mandarin Oriental in New York. Visit to book an appointment, learn more from spokeswoman Mariel Hemingway and take the Wellness Week pledge.