Walking is a great form of exercise, particularly if you haven't done much exercise before. Here are some tips from the US National Institute of Diabetes and Digestive and Kidney Diseases:
# Try to walk at least three times per week. Each week, add 2 or 3 minutes to your walk. If you walk less than three times per week, you may need more time to adjust before you increase the pace or frequency of your walk.
# To avoid stiff or sore muscles and joints, start gradually. Over several weeks, begin walking faster, going further, and walking for longer periods of time.
# Set goals and rewards. Examples of goals are participating in a fun walk or walking continuously for 30 minutes.