Wii Fitness is a fitness test on Wii Sports that tests a player's strength, speed, and stamina using training games from Tennis, Boxing, Bowling, Golf, and Baseball. Taking the player's strength, speed, and stamina into a complicated formula, the game then determines your "Wii Fitness Age" on a scale of age 20 to age 80. A digital calendar is included to track your progress. The test can only be taken once a day per Mii. (If a player quits the Wii Fitness test, he won't do another Wii Fitness test until the following day.)
If you want to do another Wii Fitness test, go to the Wii system settings, select the calendar option and change the date. Then, you will see that you can do another Wii Fitness test.