hey, i felt compelled to write because i could relate a lot to what you said. i was a pretty crazy teenager--although i'm not sure it stopped when i turned 20! first of all, sex is not bad for your cf, unless you are talking about the potential of getting an STD, which can be mostly prevented. but i understand if you see it along with drugs, alcohol as a teenage temptation. i'm glad that you are thinking about these things, because many people just DO and don't think.
i personally believe that experimentation is a perfectly natural part of being a teenager. even having cf doesn't make that different. there will be temptations for your entire life, and now is the time for YOU to start figuring out what you're comfortable with, and drawing boundaries for yourself. let me tell you, i did everything, smoked cigs, pot, drank, plus more (not all at once, i wasn't a junkie!) and the smoking really hurt me. i went from hardly any hospitalizations in years to being in there 3 or so times in one year. i'd sneak out for a cig at the hospital even--so hard headed i was.
But, my point is that this was something i had to go through. like i had to test my body or something. i had to see how far i could push myself, how "normal" i could be. (as in, normal people don't end up in the hospital from smoking.) and it was from the depths of this really bad place i had put myself in that i rose up and decided, i don't want to die, i don't want to live like this. smoking isn't worth it. my life is more important than all of that stuff--peer pressure, etc. because your real friends will understand and will like you no matter what you do. i did lose some friends when i "cleaned up", but i moved onto a much better and happier place in my life. and for once i thought about things beyond high school like getting into a good college--living somewhere else, meeting new people, having new experiences.
i'm not telling you i'm perfect now. but i have learned to put my health at the top of priorities.
hope this helps--