Aerobic fitness increases the amount of oxygen that is delivered to your muscles, which allows them to work longer. Any activity that raises your heart rate and keeps it up for an extended period of time will improve your aerobic fitness.

As you increase your aerobic fitness, you will notice that you can do more physical activity without becoming out of breath or feeling like your heart is pounding. You will be able to do activities such as playing with children, housework, yard work, or hiking without becoming exhausted as quickly. Many forms of aerobic exercise will also strengthen your muscles and increase your flexibility.

One of the best and easiest aerobic activities is walking. You don't need special equipment, and it can be done almost anywhere. To get aerobic benefit, you must walk briskly-fast enough to increase your pulse and breathing, but not so fast that you can't talk comfortably.

Some people start by walking 30 minutes daily during lunch or after work. Others start more gradually, with a 10-minute walk every other day. You can also add up exercise time over the course of a day. Walking 10 minutes 3 times a day is roughly equivalent to walking 30 minutes once a day.

Increasing your walking

A pedometer, which you can buy at a sporting goods store, can help you keep track of your activity. A pedometer will count the number of steps you take each day and help you set goals to walk more. Some people prefer letting the pedometer count the steps they walk, rather than trying to keep track of how many minutes they walk.

A good goal is to walk a total of 10,000 steps per day. Try wearing your pedometer every day for 1 week to see your usual number of steps. Then increase the number by up to 2,000 steps per day until 10,000 steps is comfortable for you. You can increase your walking in simple ways. These suggestions can get you started, and you can probably think of additional ways. You can add more steps to your everyday activities by:

• Parking farther than usual from your workplace (or get off the bus or subway before your stop).
• Taking the stairs rather than the elevator for one or two floors.
• Walking a lap inside the grocery store before you start shopping.
• Walking instead of driving for short trips. Walk to school, work, the grocery store, a friend's house, or a restaurant for lunch.