Procrastinating and being slothy is a bad thing when it comes to CF (or any disease that requires a good amount of effort). I'm a pretty lazy person by nature, and I used to be kind of the same way relating to me taking care of myself. Eventually after seeing several cystics die that were acting the same way, I told myself I didn't want to end up like them. Granted i'm not super motivated man (his movie comes out next month btw, he battles wolverine), but i've atleast been a stickler to my meds/aresols. If you are similar in nature, usually it takes a good scare CF wise to get ya to change, because that is human nature. It's like the really obese guy who remains a couch potato till he gets his first heart attack, and either it scares him into changing or he remains that way and dies too early.
As far as exercise goes, you don't have to tackle a gym and start lifting like crazy (though that would help), but try to make it a point that instead of say sitting down to play on your xbox, you get on your bike and get a good cardio session out of it. Late night jogging around the block (weather permitting) is good too. I once heard a guy say (when relating to a friend) "My friend told me he doesnt have 30 mins a day to get in shape. I told him he won't have ANY time to get in shape once he's dead". Just look to the alternative, and realize it can happen to you if things don't change. I personally used to work out quite a bit, with occasional gaps of slothiness mixed in just enough to take away a good deal of the results I got from working out for the other long periods of time. I'm currently on a month and a half of not lifting, and it's showing. I wish ya the best, and I hope you get some form of help/change of mind to make sure you stick around.