Graham Holmberg, fittest man on the planet.
(The judge behind him and to the left, Johnny Mac, was an instructor at our L1 cert last February!)
I've not had it myself, but I know some of you have had issues with breathing during intense workouts.
Here's a thread in the CF forum about asthma, nutrition and working out.
Also, if you look at the bottom of the thread, you'll find links to other related threads. Neat!
Hope this information is helpful for you!