You know that old excuse about not having the time to work out? Better think up a new one!

By introducing higher-intensity routines to your workout schedule, you can burn more calories in less time and boost fitness benefits by challenging your body in new and different ways to build both muscle and endurance, according to Joelle Mancuso, director of education for the Spinning® program.

If you, like most of us, are short on time but willing to put in 20 to 40 minutes to get in shape, Spinning® classes and Super Circuits may be just what you need.

Super Circuit: a "Super" 20-Minute Workout

What it is: An overall workout that intersperses resistance training with short cardio "blasts" to work all of your major muscle groups and elevate your heart rate to burn calories.

What you do:

Warm-up with light walking (3 minutes)
15-20 push-ups (30 seconds)
Jog in place (1 minute)
15-20 sit-ups (30 seconds)
Jump rope or jumping jacks (1 minute)
15-20 walking lunges (30 seconds)
High knee walking (1 minute)
** Repeat circuit two more times **
Cool down with light walking and stretches (3 minutes)

The 40-Minute Workout: Spinning®

What it is: An indoor cycling workout, Spinning® brings the elements of elite athletic training to people of all fitness levels. Part yoga, part Tour de France, Spinning is a mind/body exercise program that uses a specially designed stationary bike called a Johnny G Spinner® Pro and a detailed set of cycling exercises with heart rate training to achieve personal empowerment.

What you do: Adjust the resistance, handlebar position and seat height to your comfort and let your certified Spinning Program instructor coach you through an exhilarating ride — at your own pace — that includes hills and flats and is set to energized music from New Age to reggae, country, and rock and roll.

To gain the maximum health and fitness benefits from exercise, you should schedule several (40+ minute) workouts into your weekly schedule. For these sessions, Mancuso recommends her clients bolster their Spinning and Super Circuit regimens by adding resistance moves and stretching so they build their endurance, strength and flexibility.