1. EA Sports Active, it has routines for different fitness levels you find what works for you and grow from there. like a personal trainer, personalized.
http://www.youtube.com/watch?v=ZM5t9EXQrgM...feature=channel2. Gold's Gym: Cardio Workout this is kind of faster routines, more like regular gym workouts a little bit faster pace.
http://www.youtube.com/watch?v=r7l-gw34qqcBoth are excellent choices for working out, if your mom think Wii Fit it's too easy for her, get her this titles, they are very good workouts. There's also one by Daisy Fuentes about pilates and yoga, but haven't tried it, it comes out tomorrow. Probably will also be good as it's done by Sega.
http://www.youtube.com/watch?v=HrYk4sHSwwAForgot to mention that Jillian Michaels Fitness Ultimatum is the one of the worst titles available for the Wii the controls don't work. Dont buy that by any chance.