Why do we need to exercise?

...and perhaps the best reason to exercise??
You just feel better. Basically, when you get your heart pumping, and blood circulating, you release endorphins that elevate your mood, and burn calories for several hours and even days afterwards.
There are many people out there who do not exercise either due to motivational problems or ignorance of what is actually required in terms of time invested to achieve meaningful results.
The amount of training time necessary to dramatically improve ones physical condition is far less than what most people have been led to believe; at the most an hour to an hour and a half per week, and in many cases considerably less. Everyone should be able to schedule 30 to 90 minutes of their time each week for something so important.
Wrong. You can't afford not to exercise.
The cost of not exercising can be far greater than a lifetime of the most expensive personal training services. Heart surgeries can cost well over $200,000 and one must often spend as much as $5,000 per year on medication afterwards for the rest of their life. If, due to lack of exercise, your mobility prematurely decreases to the point where you can't care for yourself, you may end up spending over $3,000 per month for the last 5 to 10 years of your life wasting away in a nursing home.
So, would you rather spend a few hours a week on a home exercise program, a few hundred per year on a gym membership or a few thousand a year on personal training and make the effort to stay fit? Or end up spending upwards of $30,000 per year to stay in a nursing home and have somebody else dress, feed, and bathe you, because you no longer possess the necessary level of functional ability to do so yourself?
Like the old saying goes, use it or lose it. If you can't move, you can't do anything but lie there and wait to die. If you value your life, getting some exercise should be one of your highest priorities.