Jogging and asthma

bunnaroo

So I've been visiting the gym as my friend's guest. It's actually a lot of fun! BUT - we start each workout with a walk/jog and end it with another, shorter jog on the treadmills. I am NOT a jogger. It feels great to run, but as a life-long asthmatic, jogging for any stretch of time makes me wheeze like a little old lady. It's not like I never tried - I even got kicked off the track team in high school for having an asthma attack! (At the time, it was awful. Looking back, it's kind of funny.)

My friend made fun of me because I walked at a moderate speed while he did his jogging next to me. At the end, he got me to jog for 6 minutes - not even all in one stretch, just 2 minutes at a time. But it felt great! I remembered to use my inhaler before starting our workout, so I think that helped, but in general, I think my triggers/allergies may have changed enough that I can handle it.

The question now is this: How do I start jogging? I highly doubt that I could just do his routine (walk for a few minutes, then jog for what seems like forever, then cool down) without my lungs exploding. For a novice jogger, how do you build up steam, and when will I have that kind of stamina? What kind of tips would you offer to a beginner, with or without lung issues?

ETA: The asthma is under control with the help of medications and doctor supervision.