I never did until the past month or so. I figured I was just one of the guys that didn't and I was jealous of those that did. -Always had their own natural lube. I was that way my whole life until just recently.
Guys they don't produce it. It can happen. Precum, begets precum. If messing around slowly so friction doesn't make it vanish, I had about a drop or so to play with. In playing with that tiny amount, another drop or two showed up. Then if I did kegal, there was a "normal" amount. Not enough to soak through jeans, but enough that as friction used it up my body made more. Pretty fun transition for me and I think I always had the capacity, but was so focused on yankin it that my body couldn't keep up with making it.
By slowing down, my body makes what it needs and once there is "some" my body will keep up if I speed things up.
Anyway, good question original poster and for those that want some precum, really slow things down. If you want to know more about the specifics of what I did, I'll post.