It's in the Contemporary, not BLT. Information on disneyworld.com:
Olympiad Fitness Center
Located on the third floor of the Contemporary Tower. This spa and salon offers massage therapy, skin care, body treatments, steam rooms, saunas and the latest in fitness equipment including free weights, treadmills, elypticals, bicycles and stair climbers. Lockers are available.
Open from 6:00 a.m. through 9:00 p.m., the facility is available to Guests of Disney's Contemporary Resort 14 years of age. Guests 14-17 must be accompanied by a parent or guardian. Spa services include a surchargestarting at $50and are by appointment during the hours of 8:00 a.m. to 7:00 p.m. A personal trainer is also available by appointment.