Hannah, I went 3, almost 4 years, without doing my vest treatments, Pulmozyne or inhaled antibiotics. I simply couldn't bring myself to do them. I'd look at my vest and I'd feel a weight sitting on my chest, and it felt like a hand was reaching in and squeezing so tight I couldn't breathe. I would maybe do one or two treatments in a row, miss one and then feel like "why should I eve bother" and I'd start ignoring them again. Part of this had to do with my depression. The other part had to do with just being sick of having CF.
I could easily tell you those years were a mistake and if I could go back in time, I would. But I'm sure you'll hear that a lot and I'm sure you know it's really not a good idea to miss treatments, since you posted this thread.
What I had to do to get myself back on track was find something tangible for motivation. It was easier for me to give myself a dollar every time I did my vest than to think, "There, I'm saving my health." I didn't really care about my health at that point, but I did care about buying books. Each time I did my vest, I got a dollar I would save to buy a book. Eventually, doing my treatments became a habit and I didn't need that physical motivation anymore.
I still look at my treatments as a day to day thing. I am supposed to do 14 treatments a week; one in the morning, one in the evening, every day. If I miss one or two treatments a week, I don't beat myself up over it. I just focus on getting the next treatment in. There are still days where I stare at my vest and it physically hurts me to just think of doing it. Those are the days where every step I take to the kitchen to get my inhalers is a challenge. Hooking myself up to the vest is a challenge. Even pushing the start button is a monumental task.
I would also suggest finding a therapist to talk to. I know they can be expensive, but if you can find one that has a specialty in dealing with people with diseases, talking to that person helps so, so much. Having someone to talk to who won't judge me, who won't get that sad, disappointed look in their eyes has made a huge difference. I can't talk to my friends, because they say they understand and that annoys me because they don't. I can't talk to my parents because I know how much those years of not doing anything hurt them. But I can talk to my therapist and she helps me find the clear path so I can make the right decisions.
Please, if you ever need to talk, I am almost always around and more than happy to be a sounding board or just to listen. It takes work and focus, but it is possible to get back on track when it comes to treatments.