1. Cardiovascular Diseases - When the human body is relatively inactive for a very long time, the heart becomes weaker and less efficient than it should normally be, and is more susceptible to life-threatening diseases that can cause heart attack.
2. Obesity - Like gasoline is to an average car, food is fuel to human beings. It is our energy source. Unfortunately, if people maintain (or even increase) their eating habits from their youth, yet become more and more sedentary as they grow older, they use less and less energy as they simultaneously take in more and more. The body then stores this excess enhergy as fat,and obesity occurs in no time. Obese people are even more susceptible to cardiovascualr diseases, so it's really no laughing matter. Read more about managing the body's energy consumption on my article about Energy Balance.