Advice for running with asthma as a beginner

Hey everyone, this is my first post on reddit, so I'm very sorry if it isn't the best. This is basically my last resort because I have no one near me I can ask 😅.

So, I'm an 18 year old male in slightly below average shape with a not-so-good case of workout triggered asthma (I get winded to the point of being unable to run extremely quickly). I've consulted with a doctor many times in the past about it and I'm not at high risk of asthma attacks anymore, but that doesn't change the fact my asthma left me in pretty bad shape from being sedentary for so long. I've also been told in the past by the same doctor that cardio can help reduce the symptoms of asthma.

So, this leads me to my questions: What should my routine look like if I pick one up? How long/far should I run? How would I warm-up? What would an appropriate diet look like? I already know I should take it easier than most considering my condition, but how easy should I take it?

I guess this post is me asking for advice as both a beginner and as an asthmatic, so anything would be greatly appreciated, especially from others in similar conditions as me.

(P.S. I already know the medical precautions I should take to avoid anything bad and err on the side of caution, so no one needs to worry about that. This isn't me asking for medical advice, just workout advice for others.)