We've heard it a thousand times: Exercise is key for weight loss and staying fit. But there are days when finding time for a workout feels like a game of Jenga. It's not always possible to take a lunchtime swim or Spinning class, but I know I want to break a sweat.

In situations like that, I used to skip exercise, and just chalk it up to having too much to do. Then I met Jillian Michaels, the supercalafragalistic trainer who can help even the busiest people carve out time for cardio and motivate staunch exercise avoiders to happily climb on the elliptical machine. Besides being a fitness pro, Jillian is also a new contributor to SELF. So I asked her for ideas for how to make short workouts even more effective so your track to shed stubborn pounds is even speedier:

Crank it up
"On days when you have very little time, try anything that's super high intensity," Michaels says. "Sprints. Stair climbing. The less time you've got, you really want to burn as many calories as you can so you're getting a greater after burn. You want to work super hard so anywhere from 2 hours to 24 hours afterward you're getting a greater calorie burn because your body is trying to recover from the workout and returning to what's called the pre-lactate state." Try this high-intensity workout at Self.com.

Switch things up
Variety is important because the longer you stick with a program, the more efficient your body becomes at doing it. That means you use less energy and burn fewer calories with subsequent workouts your body adapts to whatever activity you regularly do and stops getting results. "Doing something new, even for 15 minutes, will shock your body into working harder," Michaels says. "I loop clients through rowing workouts, elliptical workouts, StairMaster workouts as well as swimming, kickboxing, Spinning, and running. I put them through every different kind of cardio, every different kind of training, and even the way I use a piece of equipment will change. On the treadmill, some days we run backward. Some days we'll run wind sprints. Some days we run at an incline. Some days we're incline walking. Some days we're doing long-distance running. You don't want your body to adapt and you want to make sure you're working out enough."

Make it fun
You'll work a lot harder to fit in a sweat session if it is actually enjoyable. "If there's something you want to explore, try it!" Michaels says. "Do a kickboxing class. Take a dance lesson. Work out with a friend. Keep it social. It's really important because when it becomes tedious and sort of mundane and rote, it's going to be another incentive for you to quit or stop."

Sneak in fitness
Once a day, spend 10 minutes doing something that leaves you winded. Jump rope or skip to your car. Anything that adds to your day's total calorie output equals a leaner, fitter body.

Go for the gusto
"Push yourself!" Michaels encourages. "You're so much stronger than you would ever imagine. Your potential is so much greater than you would ever believe it to be and when you take that chance and become vulnerable and engage in confronting your fears, you'll find that your physical strength will transcend into every other aspect of your life. So be brave, be courageous. Every little accomplishment that you create it will help you realize that you can achieve more."
 
Get more quick moves and plans at Self.com/fitness or join the SELF Challenge for simple moves and meals to help you uncover your best body ever.