But there is more to the story of the sculpture than this. Michelangelo's David's physique was different because the Renaissance artists had been looking at the sculptures of ancient Rome and Greece. And there was a particular ideal of the male body at the time that has lead us to say right up to this day, "the body of a greek god". And in spite of the fact that it is supposed to be David from The Old Testament, Michelangelo carved the body of an ideal from the ancient world. And this was a body developed for the Olympics. This not a body of raw strength, this is a body of athleticism, and graceful movement.
If you want to have a body like this, you have to consider yourself a bodybuilder, not a weight-lifter. If you want a body like Goliath (not pictured), go ahead and lift the heaviest weights that you can find. Don't worry, no one is going to knock you down with a pebble in a slingshot!