Building off the critical success of Wii Sports and its popular "fitness test" mode is Wii Fit, a collection of more than 40 activities and games specifically designed to get players off the couch. Packed in with Nintendo's Wii Balance Board, a squat rectangular object resembling a common scale, Wii Fit spreads its activities out across four different categories: strength training, aerobics, yoga, and balance training.<br><br>Players begin by entering their height on the screen and then standing on the Balance Board to determine weight and body mass index (BMI). After users' BMI has been calculated a balance test, based on how well players can control their left and right balance, determines players' Fit Age.<br><br>Users can then begin to try out the game's many activities. Strength training focuses on muscle toning, and includes exercises like single leg extension, torso twists, and rowing squats, as well as push-up, plank, and jackknife challenges. Yoga activities stress balance and flexibility and incorporate deep breathing and poses like half-moon, standing knee, and downward facing dog. Heart-pumping aerobic exercises include advanced step, rhythm boxing, and free run, while the balance games include soccer heading, ski jump, tightrope walk, and penguin slide.<br><br>Wii Fit uses graphs and charts to keep track of daily activity, lets users input data from non-Wii Fit exercise, and players can set goals for reducing their weight and BMI. Up to eight players can create and keep a personal profile in the game, letting family members check one another's progress and form friendly competitions.