Most experts agree that 3-5 times per week is sufficient. Frequency, duration and intensity. Frequency refers to how often you perform aerobic activity, duration refers to the time consumed during each session, and intensity refers to the percentage of your maximum heartrate or heartrate reserve at which the activity is performed. Since muscle weighs more per volume than fat, and you want to have firm muscles throughout your body, you may weigh more than you thought was average for your height and build. There is no ideal bodyweight.
Aerobic exercise is any activity that rhythmically uses large muscle groups.
Aerobic activity increases the heart, lungs and cardiovascular system's ability to deliver oxygen more quickly and efficiently to the body. As the heart muscle becomes stronger and more efficient, a larger amount of blood can be pumped with each stroke thereby decreasing the number of strokes required for oxygen transport. An aerobically fit individual can produce more work for a longer period of time and recover faster. I have never exercised before. Walking is the best way to begin a program.