Many people want an easy exercise routine that you can do from the couch. Well, you can! Sort of. It does take a little bit of work to make it happen.
The human body is designed to expend as little energy as possible. To do this, the body adapts to the demands placed upon it. Our bodies have perfected this conservation due to our highly adaptable qualities. One way you can combat this is by maximizing the amount of calories burned in a workout session. By maximizing calories burned, you're also maximizing the O2 consumption needed for the workout and recovery. This recovery oxygen consumption is known as EPOC. Excess post-exercise oxygen consumption.
EPOC is the elevation of the body's metabolism after exercise. This means that the body is burning more calories following exercise than before the workout started. EPOC is like a car engine that stays warm after you've been driving around. After exercise, the body must utilize increased amounts of oxygen to replenish energy supplies, drop body temperature and return to a resting state.
Research has indicated that the higher the intensity (percentage of HR max) of the training session, the greater magnitude of EPOC. It has also been shown that splitting the workout into two (doubles) of equal time has the greatest effect on EPOC.
So in your workouts, work hard. Try two-a-day's. When you maximize your intensity, you'll still reap the rewards while you're sitting on the couch.