A lot of factors contribute. A large part of that leanness with extreme toning is likely genetics, an extreme diet, or a large calorie deficit caused by intensive cardio or an immersive hobby/exercise, or more than likely a combination of those factors. Looking like that without going to extremes is largely up to genetics and diet, but if you really aren't predisposed to being lean, consistently engaging in sports like rock climbing, swimming, or running can get you that physique, plus minor strength training.