Life Expectancy Positively Impacted By Moderate To Vigorous Physical Activity

Pooled data from six studies in the National Cancer Institute Cohort Consortium show that exercise can increase your life expectancy regardless of your weight.
A physical activity level equivalent to 75 minutes of brisk walking per week showed an increase of 1.8 years of life expectancy relative to no activity while 150 minutes per week of the same activity resulted in a 3.4 - 4.5 year gain.  This was evident at all body mass index (BMI) levels and also for black individuals and former smokers.
While keeping your weight at a healthy level should be your goal, exercise can add years to your life regardless.

Leisure Time Physical Activity of Moderate to Vigorous Intensity and Mortality: A Large Pooled Cohort Analysis