A 45-year study out of Sweden has found that a life long habit of low levels of aerobic exercise predicts death risk. In terms of lifestyle factors that contribute to a shortened lifespan, lack of exercise is second only to smoking.
Considering that aerobic exercise essentially trains your heart and lungs, improves the circulation of oxygen and removal of waste products to and from each and every cell in the body, and helps to relax and calm the mind, this should come as no surprise.
So how do you get started with building up your aerobic fitness? The important thing is not to do too much too fast. This will only lead to injury and disappointment. Avoid going from couch to jogging or boot camp style workouts. Instead, start with a brisk 30-minute walk every day. Walk the dog. Go on a hike. Ride your bike. Ride your bike to work. Play a friendly game of basketball or tennis. Do some yard work. Basically get out there, and make it a regular thing. You will be grateful for every minute of life you buy yourself by staying active.