Increase Activity
You don’t need to adopt an aggressive exercise routine; just increase your physical activity throughout your day.  Do what is right for you and your schedule.  The key is to increase physical activity.

Simple activities or changes to routines can make a big difference. Instead of sending a co-worker an email, walk over to their desk next time. When you clean your house try doing it as fast as you can. Take an after-dinner stroll. Use a treadmill while watching television. If you take the bus, get off a stop or two from your destination and walk the rest of the way.  Opportunities to increase your daily activity levels are all around you.

Choose to walk. While there are a number of excellent ways to give your body the exercise it needs, walking is the most natural and normal activity for most people. Walking requires little planning and no equipment. Research has shown that walking (brisk or power walking) can be more beneficial and effective to overall health than extended running workouts.

Everyone can walk, any place, anytime, with no learning curve. Also, walking is safer and there's less risk of injury for people who are just starting to exercise.