Exercise routine and ASD

I got a exercise routine and have been using it for years and years and years with no luck. I went to the gym and did workouts especially for the knees and did them 3 times a week for 2 years and still with no luck. All my effort at the gym would ware off in a day and I worked out for over a hour each time I went and the results just never happened. I do not think that my muscles are able to strengthen. They are missing some key ingredient to make the muscles retain the workout.