When do I add weights and how much? I'm glad you asked that question! Use the following guidelines: when you are able to do the scheduled number of sets and reps in a given exercise, increase the weight by the smallest increment possible, e.g., on the bench press if you can do all 3x15 with the weight of the bar only, add a 2.5lb weight to each side and use that until you can again do 3x15, then take the 2.5lb weights off and use two 5lb weights and start the whole process over again, and on and on.