Get Fit in 90 Days: Week 5 (The Plan)

"By adding cardio to every workout and working in intervals, you'll be able to push your limits and end up with amazing results," says Sara Haley, of Sara Haley Fitness and the creator of our 90-day workout plan. "Think about it: If you knew you had to do something for just 30 or 60 seconds, wouldn't you give it your all?"

Monday: Cardio Session

You'll need a stop watch or a clock that you can easily see during your workout. Head outside or jump on a treadmill and warm up for 5 minutes with a nice walk or jog. Today, we'll be spending less time in your "comfortable" zone and more time in your "uncomfortable" zone. Whether you are walking, jogging, or running you need to pay attention to how it feels in your heart and lungs. These are the muscles we are trying to make stronger.

• 0:00 - 5:00, warm up with a walk.

• 5:00 - 8:00, find a pace you find challenging but manageable.

• 8:00 - 8:30, push to a place where you think you might lose your breath. You should feel like you couldn't possibly do or give any more. (This is referred to as working anaerobically or without oxygen.)

• 8:30 - 9:00, recover

• 9:00 - 12:00, jog

• 12:00 - 13:00, run or sprint

• 13:00 - 13:30, recover

• 13:30 - 16:30, jog

• 16:30 - 18:00, run or sprint

• 18:00 - 18:30, recover

• 18:30 - 21:30, jog

• 21:30 - 23:30, run or sprint

• 23:30 - 28:30, cool down

Tuesday: Upper-Body Circuit 1

Start with a 3-minute warm up of jumping jacks, jogging in place, or jumping rope (or, a combo of all three for one minute each). Then, choose one to repeat between each upper-body exercise below. The time you spend doing each will increase each round. You will need one set of dumbbells between 5-8 lbs. Click here to see how to do the exercises below.

• 12 chest flies on each side (targets chest); 30 seconds of jumping jacks, jogging in place, or jumping rope

• 12 reverse flies on each side (targets back and shoulders); 30 seconds of jumping jacks, jogging in place, or jumping rope.

• 12 front raises, 20 bicep curls, then 10 combo curls (a bicep curl, then a front raise), while standing cross-legged or on one knee (targets shoulders and biceps); 30 seconds of jumping jacks, jogging in place, or jumping rope.

• Lie on your chest with your legs long, arms in a T formation, and your palms facing the ceiling. Holding the weights on your palms, lift them up off floor and hold for 2 seconds. Repeat 10 times. Then, do 30 seconds of jumping jacks, jogging in place, or jumping rope.

Do this circuit two more times, but increase your cardio intervals to 45 seconds during your second run through, and 60 seconds throughout your final circuit.

Wednesday: Cardio Circuit

Warm up by holding a 30-60 second plank. (See how to do it here.) You'll complete each of the below agility exercises for one minute each, and complete the circuit four times. Rest for one minute in between each circuit. This workout should take you less than 30 minutes.

• Quick toe taps: Find a short elevated surface like a step and hop from foot to foot, quickly tapping each toe on the top of the surface.

• Side shuffle right and left

• High knee runs: Run in place, but aim to get your knees to your chest. Engage abs to pull your knees up even further.

• Skaters: Shuffle two steps to the left, and twist your body so that your left leg and right elbow shoot back as if you were speed skating. Repeat on the right side.

• Butt kickers: Hold your arms in the air and jog in place, making sure to try to kick your butt with each step.

• Jumping jacks

Thursday: Cardio Session

Repeat Monday's workout followed by Tuesday's Upper-Body Circuit. Don't worry though—you're skipping the card intervals in between each exercise!

Friday: Fitness Class

Challenge yourself with a fun new cardio class. Visit a kickboxing gym, take a Zumba class, or rent an aerobics DVD.

Sara Haley (sarafitness.com) is a Fitness DVD Personality, Master Trainer and Creative Consultant for Reebok.