Starting a walking program is safe for most people.  However, if you have been inactive for some time, you should consult a doctor first.  Once cleared to begin, we recommend starting with an easy 20 minute walk.  Repeat this workout 3 more times in the first week.  If you feel good, then add 2 minutes/workout each week until you are walking 30 minutes 3 to 4 times a week.  From there you can follow the 10% Rule described below.

It is recommended that any increase in walking time be limited to no more than 10% greater than the previous week's longest workout (e.g., if 30 minutes was your longest workout, then do not exceed 33 minutes of continuous walking in the subsequent week).