If you want to break a sweat with your Wii, EA Sports Active is the way to go.
What's great about EA Active is that you have many different workouts to choose from, whether it is all-body, cardio, or sports. You also have the option to create your own workouts, in case you get bored with the available choices. For example, you can have a workout that has lunges, squats, running track, and a few dance moves. Or you could have an all-sports workout with some baseball, basketball, boxing, tennis, and volleyball drills. The choice is yours. The 30-Day Challenge is a nice touch, as it will throw random workouts each day to not make a chore to participate in these drills.
I do have a few minor complaints about the game. The resistance band that they give you is terrible. It looks more like the ones that you do pilates with. Perhaps if it was a tubed band with medium resistance, it would have been better. As far as the game goes, it doesn't put you on the spot for missing workouts as Wii Fit does. You don't have your training coach saying "Too busy to workout yesterday, eh?" Or "Why are you missing your workouts?" Nothing.
Still, these are just minor complaints. EA Sports Active is a great way to get in shape through you Wii. Highly recommended.