I'm a really slow gainer. I have been working out for 30 years off and on. I am in relatively good shape. I have done all the basic body building exercises during those 30 years, but have never put on any real size. I have used all sorts of weight gain powders, but really haven't stuck to the prescribed amounts. In my opinion the prescribed amounts are normally ridiculous. Genetically for body building, I am doomed. I am tall and skinny. I have eaten like a horse for part of those years, but really can't now that I am 50 years old and have put myself on a heart healthy diet. On top of eating my Styrofoam diet like a horse, should I be working out with the heaviest weight I can possibly lift? I don't normally press myself to lift heavier and heavier weights. I have never been able to lift heavy weights and still be able to do the normal (6-10) suggested reps. I normally do 3 sets of each exercise and finish those sets in relative exhaustion without trying to overwhelm myself with extremely heavy weights which would cut down on the amount of reps that I could do. Is this where I am going wrong. Should I be going heavy as possible? Instead of going through a full range of motion on each exercise, I have noticed some of the big guys in the gym doing short range pump up movements where they never fully extend and have a resting point. Is this important?