Next time you go to a kid's birthday party steal a candle from the cake.
Hold it a foot from your yap and lightly blow. Unless you have emphasema, that flame will be extinguished.
Re-light that candle and again hold it a foot away. Breathe in as hard as you can. Flame still burning huh.
Well move the candle a little closer but be careful not to exhale on it. Still lit, move it a little closer and try again..
See if by the time you can extinguish it by inhaling you end up burning your lips.