I'm still early stages on studying steve Huston anatomy

I get the theory that legs make half of the body and they are at least 4 heads long.

But my mind has a hard time processing the lenght of them like in the pic.

That is when I draw the torso everything is fine. But when I get to the legs my mind "can't believe" they are as long as they are and I make them shorter than they should be.

pic related as those legs are long and beautifully drawn.

Any advice?