I use a peak flow meter. It definitely helps me to guage when somethings going on. It also helps me to bring stuff up. I also have a different device i got from when my mom had her surgery. They gave her this thing where she had to take a breathe in and keep it between these two markers. It is to help strengthen the lungs after a surgery. I asked the nurse if i could have one and explained i had cf and she snuck one out to me. It also helps me to cough stuff up . I always wondered why our doctors dont give us these and have us use these on a regular basis. They seem to be of help in keeping the lungs open and flexible.