Why lead with the left?

Did you ever wonder why so many martial arts train with the left side forward? Did you ever wonder why some people just cannot seem to take a punch to the body? Well, check this out:

Video courtesy of www.youtube.com/@KentoBento(©)

The liver is vulnerable on the right side of the body just below the floating ribs; it is also vulnerable straight into the solar plexus, just below the xyphoid process of the sternum.

There is a reason behind everything you are taught; even if you do not realize it.