To lose weight and get the most effective workout, it's important to include cardio or aerobic exercises.  These types of exercises use large muscle groups to increase your heart rate and breathing pace.  It should be sustained for at least 10 minutes at a time at a minimum.  Most fitness DVDs will incorporate some aerobic activity since this is one of the best ways to induce weight loss with exercise.  Common forms of aerobic exercise found in fitness DVDs include:  dancing, interval training, running or walking in place, and calisthenics. They also might incorporate isometric exercise, which strengthens specific muscles or shape the figure by pitting one muscle or part of the body against another or against an immovable object in a strong but motionless action, as by pressing the fist of one hand against the palm of the other or against a desk. Make sure to do about 150 minutes or 2 1/2 hours of cardio each week.  To help induce weight loss, you may need to increase the intensity or the amount of cardio exercises you're doing each week. Resistance training is a type of exercise that helps build and maintain lean muscle mass.  Incorporating regular strength training is another important component of weight loss and physical activity.  Exercise DVDs use a variety of equipment for strength training exercises, such as dumbbells, kettlebells, and resistance bands or tubes. You might also do body weight exercises (as used often in Pilates) and isometrics (as used in yoga). Weight training has shown to help increase muscle mass and metabolism which can aid in weight loss.  It's recommended to include resistance training on at least 2 days per week.  Note that many DVDs offer a combination of aerobic and strength training exercises in one program that could help cut down on overall exercise time.  This may be a smart option for those with little time or very busy schedules. Stretching and flexibility is an important part of your fitness routine.  Studies have shown that stretching may help prevent injury.  Try to include stretching after each workout session.  Many DVD programs automatically include this at the end of each workout or routine. Yoga is a great practice to help stretch, relax and restore your body after a week of exercise.  Some DVDs may have a stretching routine included.  However, you may want to consider purchasing a separate DVD for stretching and recovery routines. In addition to incorporating the recommended amounts of activity each week, it's equally important to include adequate rest and recovery days.  Studies have shown that allowing your body to rest and recover may help prevent injury.  Rest days can also be active.  Light walking is something that's appropriate to include on active rest days.

Summary:
Include cardio-based DVDs. Incorporate a few days of strength training DVDs. Include flexibility or stretching DVDs. Plan for 1-2 rest days.