Wii Fit Cheats

Unlock Challenge mode in muscle workouts
Get a 4 star on both reps in Press up and side stand , the Jackknife and parallel stretch to gain the challenge mode for this workout

(Note: to gain the 2nd workout/ reps you need to do well in the first one so that the trainer tells you that you are doing well and should go for more reps/ seconds.)

Jackknife challenge: Get a four star in both the 10 sec workout and the 20 sec workout to gain the Jacknife challenge
Parrallel stretch challenge: Get a four star in both the 30 sec and 60 sec workout to earn the parrallel stretch challenge
Pressup challenge: Get a four star on both the 6 reps and 10 reps mode to unlock the Pressup challenge

Unlockable Games
As a General rule to unlock new features play the previous games or complete the highest amount of reps or do more Body tests.

"Ok stamp": Attend 2 Body Tests
"Star stamp": Attend 5 Body Tests
Free Jogging: Do the Island lap 2-3 times
Free step: Play Step Plus Aerobics 2-4 Times
Longer Jogging Routes: Play the highest one to unlock the next one up 2-4 times
Step Plus Aerobics: Play step Aerobics a 2-4 times
Tightrope Advanced: Complete Normal Tightrope
Tightrope Super Advanced: Complete Advanced Tightrope