True story.
A few years ago while fishing with my grandsons, we are catching crappie good. I told the younger gson (they were in mid teens), you can tell a good angler from their thumb. If it is roughed up and sore, they're a catchin' machine. He proceeded to want to take off all fish caught. He would rub his thumb on their mouths to roughen the thumb. He didn't know I was watching. Later, I saw him playing in the livewell, roughing his thumb.
On the way home, he was so proud when he showed his PawPaw his roughened thumb.
Here he is this summer. This is Thibault, he's soon to be 17.