Myth #1: Longer Workouts = Better Workouts
With most goals exercise quality is more important than quantity. Smart exercise will always take precedent over long exercise. Each workout has 2 primary variables: intensity and duration. Try to workout at a certain intensity so the duration is limited.
Not controlling your workout intensity and spending too much time in the gym is actually bad for your body because your body will produce excess stress hormones which will hinder the recovery process.