How much exercise and what kind do I need to do to lower my resting heart rate? I walk about an hour a day at least three days a week at about 2.0 MPH

Faster walk. You may need to walk faster than two mph. A good goal is to walk a mile in 15 minutes. Once you can do that your heart will be in better condition and this may decrease your resting heart rate. Check with your medical provider to see if it is safe for you to increase the speed with which you walk. The more often the sooner you see benefits.