Problems getting back in shape

Hey all, new here. So I'm a 21 yr old woman who used to be very active in high school; I played varsity soccer and varsity lacrosse, and could run for miles without stopping (my PFTs were always around 90% predicted and higher, and I didn't need IVs to fight off infections until I was 19). But for the last three years of college, I've gotten very out of shape. (And I'm not talking about getting fatter, my BMI is a healthy 21.5). The problem is my lung function has declined seriously in the last few years, which I know is so obviously connected with my lack of exercise. I know that if I want to be healthy I need to get back in shape... but even walking up a set of stairs makes me have a coughing fit. Every time I try to get in shape slowly (walking for 30 mins a day, doing pilates) I always follow it for about a week before giving up because I don't feel any improvements and its a major time drain (as a full-time college student doing 2 internships this semester, I really don't have time to commit, since I already spend over an hour with my vest and nebs every day). Today I decided to jog on the treadmill at the gym. Bad idea. After 13 minutes I was coughing so much and my heart rate was racing over 200 bpm and I had to stop, and when I got back to my apartment I collapsed onto my bed and instantly fell asleep for three hours (and missed class because of it). I'm so discouraged. Even as I type this I can't stop crying because I'm so frustrated with my health... it seems like...
Source: Cystic Fibrosis Exercise and Fitness Forum - Category: Respiratory Medicine Authors: Tags: Exercise & Fitness Source Type: forums