The Boy, who is very knowledgable about such things because his grandfather was a professional weightlifter and instructed him as a teenager, is very adamant that lifting the heaviest weight you can manage for 5+ reps is the best thing you can do. I believe studies into bone density etc bear him out on this.

Sadly, I am such a weakling that I cannot get the technique right and have hurt myself every time he's tried to instruct me :(