I recommend to read or least checkout Georg Hackenschmidt's book "The way to live" from 1908. It's free and accessible on url: http://www.sandowplus.co.uk/Competition/Hackenschmidt/wtl/wt...

As semi-pro strongman and powerlifter, i've to say that Hackenschmidt's book has been most helpful for me, because it's give good tips about diet, mental preparedness and encouraged to do other sports than just Gym.