If you've never exercised in your life, you don't want to start off too strong. If you do, you'll end up hurting yourself. Since your goal is to help your body, and not to hurt it, you need to start off with a beginner's exercise. Once you become a pro at it, then you can move on to the more intense exercises.
If you aren't as fit as you'd like to be, try this 15-minutes workout for complete beginners, brought to you by Pop Sugar:
It doesn't matter how much experience you have, because this workout will help you get fit! Are you going to do this exercise routine today?