I am 66 and signed up for a 5K in February - Started C25K this week and did not realize it's just 3 days a week, so I did the first week in three days. I love it = I will do the first week workout for three more days then start the second week. Feeling great and powerful. I am a walker, and want to bump up the calorie burn, so running/jogging here I come. Used to do hurdles and sprints in high school - so long ago!