A 40-minute toning/ cardio interval mix from The Firm. There's also a 15-minute bonus, super-calorie burning routine. Rebekah Sturkie instructs.

Intermediate exercisers. The cardio intervals are high impact and there's lots of plyometrics (jumping), so your knees should be in good shape (if they're not, there is a modified, low-impact option but it's not anywhere near as intense). You will need three to five pound dumbbells, or The Firm's CardioWeights System.

I am starting to warm up to The Firm's latest incarnation. Last year, I was a bit disappointed that they toned down the workouts a notch or two, and so were a lot of other exercisers, which is why none of their DVDs made my favorite 2008 list. Sturkie makes the most of The Firm's four-limbed approach, and she raises the intensity in the cardio segments with big plyometric moves. You're really airborne! (And yes, there are less intense modifications if you don't want to jump around, but honestly, the plyo is half the fun.) Most of the routine consists of standing exercises (squats, plies, lunges or "dips," as they are called here, all layered with arm and shoulder work), alternated with the power cardio intervals. During the last few minutes Sturkie takes you to the floor for more chest and ab work, and she still uses the four-limbed approach to add intensity to the exercises. This was a very satisfying workout — it hit just about all body parts and the cardio was exhiliarating. If you only have a few minutes and a bunch of energy (and calories) to kill, go for the bonus calorie-burning routine. If you're feeling ambitious, you can do both the full routine and the bonus workout for nearly an hour of fun and sweat.