I have been running consistently for about 9 months - that is 3 - 4 days a week. Last Saturday, I was able to run an hour without stopping, at a slow pace. But, even though I can do that, I have to push myself through the first 3 or 4 minutes because I can hardly breath. Then, it gets some better. I think mentally I still can't imagine that I can run and I panic when I start and think about how far I have to go. I try to force myself to breath in for a count of 3 or 4 and then breath out for that same count. It seems to help some. Also, slowing down is a good idea. I have read that you should do an easy run one day and hard run the next time. Hard can be longer at a slow pace, or same distance at a faster pace. The easy runs you should be going slow enough that you can carry on a conversation. The faster pace runs, probably not all the time. Doing this will increase both your aerobic endurance and help with speed.

Hope that helps some.