There are guys in the French Foreign Legion built like that, and there are guys in prisons throughout the world, also built like this guy.
The 'secret' is time and motivation. Do you think those guys who are incarcerated have access to pharmaceuticals ? No - but what they do have is time, and the motivation to be top alpha male in a hostile environment.
Not saying everyone can.match Greene, but there are many who do, even at age 40 plus.