I know there are doctors with CF out there, so it's possible. In particular I recall one who went to my clinic. I never met him, but remember reading a bit about his experience. He made it through residency, but said he regretted it, and if he had to do it again, wouldn't do it. His explanation was that it was too time intensive and as a result he slacked on self-care. His health slipped substantially and in a permanent manner. It's a lot to lose. However, this all happened a number of years ago, and it's just a single example.
I used to want to be a doctor. I opted out basically because I didn't think I'd be able to handle the hours residency requires. I think that was an accurate assessment. TO keep myself healthy, I need plenty of sleep and time to exercise. I have many friends in residency. It's pretty clear to me that I'd be run into the ground pretty quickly. All that said, if you're interested in medicine, by all means study it! Make the decision down the road when you have more information. At current, I am working towards a PhD in Biostatistics, (the statistics behind clinical trials and epidemiology). I may not be a doctor, but at least I get to contribute to the medical field in my own little way. Not all is lost if you choose not to be a doctor.
