i just started shooting a bow about a week ago. it is an older one with not a whole lot of letoff (55%) and 50 lb draw weight. have been shooting 20 arrows or so a day and i seem to be getting stronger. from my little experience it doesnt take long. i expect to be shooting 60lbs by next season. there is a muscle building device available for like $20 at cabelas or bass pro. it builds and tones only the muscles needed to pullthe bow back. it is ajdustable 50 lbs to 100 lbs. i would get the catalog and have more details, but i used it last night to build a target.( box stuffed with paper and thick agazine in back for added support all duct taped shut. only one pass through with field pts and that was when i hit the corner of the box) hope this helps and welcome to the sport.