There is only one thing that you need from an exercise program – that it works. By which, I mean that it keeps us fit and helps us lose weight (or maintain our weight goal). There are a couple of important nuances though. A great workout should be efficient (I don’t know about you, but I don’t have three hours a day to devote to sculpting my body). An outstanding workout will actually change your body shape – at any age. Here are the Five Best workouts that we found in 2010.

Jackie Warner Circuit Training. Just 20 minutes a day will change your body and you’ll see results within 10 days. And I swear this workout keeps my weight off, converting fat to lean muscle. What I like about these exercises is that they are straightforward, tackling upper body, core and legs. In fact, there are two exercises for each muscle group. I am left sweating and having to push myself to get through the third round. For me, this is just the right level of challenge; I want to feel pushed but not like a complete fitness failure who can’t keep up with some TV host superhuman. Read more on Jackie Warner's Circuits.

Couch To 5K. No matter how good Jackie is, you need to dedicate some time to pure cardio exercise. And what better than a run. But you hate running, wouldn’t even run for a bus… Think again with Couch To 5K. The simplicity makes it almost infallible.  The overall sentiment seems to be that if you can dedicate 20-30 minutes a day, three days a week to getting your run on, and if you follow the very clear and efficient guide that Couch-to-5k provides, you can complete a 5k at the end of the nine weeks.  Although the Couch-to-5k guide is free, there is an upgraded version available through  ($19.95) that allows you to track your progress online, receive e-mail reminders, and have access to more training tools.  There are multiple apps out there to track your progress, including an actual Couch-to-5k app for the iPhone ($2.99) and your iPod.

The Bar Method. I tried this workout after discovering that it helped Kelly Osbourne lose weight. Core Fusion and Barre3 are in the same genre and are also very good. But since I have to pick one, it is The Bar Method – mostly because I find it a little more challenging and it focuses a little more on the butt and thighs – definitely where I need to work. The Bar Method promises that you’ll look good in jeans after this workout and I can say that its true! Really, my thighs are leaner. Read more on The Bar Method.

Hold It! Not exactly a workout, more of a manual about how to choose the right workout for you based on your body shape. I was skeptical at first, but found that over the summer and fall I had gradually shifted my workout programs to fit with the "Hold It" theory. It turns out that for years I had been doing the wrong exercises for my pear shaped body. And with more of the right kind of exercises, I am a lot less pear. Before you launch into your New Year’s exercise regime, find the right exercise for your body shape. The first book is called Hold It and the more recent version is Escape Your Shape.

PACE Interval Training. There is a lot of research to back up the theory that short bursts of intense activity followed cool downs, repeated many times are more efficient at getting us fit. You will also achieve more in 20 minutes of interval running than you will jogging steadily for an hour and a half. PACE is not the best book in the world, but its suggested workouts are really clear and useful. I used them to adapt my running and rowing machine workouts and they were a revelation.