I was just wondering if there was any proof that breath holding exercises strengthened lungs. This is something I started doing when I was a small child with my friends to see who could hold their breath the longest, and it is something that I still do to this day on a fairly frequent basis, not while diving of course. I know it sounds likea silly thing for an adult to do, but I also find that it helps me relax and calm myself when I am mad. I realize people are probably going to think I am nuts, but the only way I know to get an answer to a question is ask it. Thanks!