Occasionally, there are optimal bodies that are made only for learning martial arts, and one of them is the Heavenly Body, which is said to be the most excellent body for learning martial arts[1]. Once in a thousand years, a person who possesses this body will be born, in which case they will have a superior achievement compared to the others since their body is more suited to learning martial arts.
Aside from this, there are other bodies that are equally as good, but most of them come with risk and side effects, so it isn't worth knowing about them. Such as some people that are claimed to have an excessive innate yin or yang, but despite having such incredible energy, they don't live past the age of 20.
From the variety of bodies, there's the Heavenly Killing Star which is comparable to Heavenly Body[1].