It's easy to get stuck in a rut with your strength and cardio workouts, doing the same exercises at the same pace day after day. But, it's always easy to add some variety to your workouts while burning more calories and boosting your endurance. One way to do that is with interval training
. The concept behind interval training is simple: add bursts of intensity (either with speed, resistance or anaerobic-type moves) throughout your workout. The idea is to work very hard for a period of time - that means really pushing your limits - then slowing down for a period of time to recover.
There are two basic ways to do interval training:
Measured intervals. With this type of training, you work hard for a measured period of time or distance and then recover for a measured period of time. This Beginner Interval Workout offers an example of measured intervals.
Varied Intervals. In this type of training, you simply work harder for as long as you can and then recover for as long as you need to get ready for the next hard interval. For example, if you're walking or running outside, you could choose something in the distance and sprint to it or walk/run up a hill as fast as you can and walk down to recover.
There are other great resources out there for guided interval workouts to really challenge you. My favorites are Cathe Friedrich's Imax 2 step intervals and Cardio Coach's Guided Interval Workouts.