Persistence and the Cardio-Cranium Malaise

So tonight we went to the gym, and we only had 40 minutes, but I wanted to try to run/walk 3 miles. I only made it through 2.5 and some stretching, but I pushed myself. I tried really hard to run 1 mile without stopping, and I pushed, and I pushed and when I thought I couldn't push any harder, I pushed a little more and almost blacked out. Ha ha. When I started (and have since been continuing) to go to the gym consistently, I could barely run for 1.5 minutes without huffing and puffing, and finally quitting--which ended up resulting in my abandoning the gym after a mere 2 weeks (or less). I have been persistent about going, and I have tried really hard to push myself a little more each week. Not to say the asthma medicine hasn't helped (tremendously), but today, I actually ran for about 10 minutes and I'd like to give my lungs credit for all their hard work. How do you get from 1.5 minutes of running without stopping, to a little under 11 minutes of running without stopping? Persistence, and endurance. However...today my persistence paid off by my being able to go a little further, a little longer--but I also got this really great headache that was just as persistent (and most likely will endure just as well until I take some lovely little advil...) and gets worse when I bend over...as in when I stretch. One day, I'll run a 1/2 marathon. :) I decided it's not ideal to "train" for a 1/2 marathon, and try to lose weight at the same time. As much as I love the weight loss shakes I drink for breakfast and lunch, they just aren't the greatest source of energy for enduring the labored huffing and puffing of trying to run a mile...*sigh*