Bodybuilder pictures inevitably raise the question " WHY?"
With some of them, the answer to 'how' is a lot of training and a lot of steroids I'd guess! Not sure on the 'why' though

Why does Mo Farah run long distances? Why does Usain Bolt sprint? Why did Lance Armstrong ride a bike?
Answer any of those 3 and you'll get an answer to your question as well.