Building up in draw weight is simply shooting a few more shots at the heavier draw until your strength increases. Unfortunately, this is so easy to say, but one must take care as to how many "extra" shots to make. Go slow, and don't rush it. When tiredness starts affecting your form, stop for the day. Shooting up to 36 arrows a day shows that you are getting close. Don't do like I did, though. I went from 58# to 78# with the simple writing of a check to purchase a bow, so I can truly say, "Do like I say, not like I do", as I had numerous problems. Remember, slow and steady will get you where you want to go.