How do I run faster?

I have CF and I joined a gym a little over a year ago and in the past 10 months I've kicked it up a lot. I'm in the best shape of my life but my endurance is still limited due to my CF. In gym last year when I had to run the mile I finished in 10:47, the only category in which I didn't get high fitness and this year I finished in 10:27 getting high fitness in everything else, I ran the first lap which is 1/4 of a mile in 1:23 but everything went downhill cause I couldn't breath. Yesterday on the treadmill I tried to run a mile in 10:00 and when time expired I had ran 0.96 miles and I'm very disappointed in myself. How do I run faster?
How do I run faster?
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