I agree.  Running outside is MUCH different than the treadmill and takes some time to get used to.  I made the transition at week 5 in C25K.   It took some time, but I adapted and now MUCH prefer to run outside.  I am even planning to run outside during the winter (accumulating cold weather running gear already.)  Just stick with it and you will adapt.

jeannette

I can tell you that running outside in heat and humidity kicks me in the behind, and I can barely make it.  That may be the issue.  Before you get discouraged see how you do back on the indoor track.  I too run on an indoor track most of the time in the summer.  My last attempted outdoor run was a disaster.  I felt like I was running with a wet blanket over me and had to end up walking (98 w/90% humidity).  Just a no go for me. 

sometimes i feel like i am out of breath too, and usually the reason is i am breathing too fast.  when i can slow down my breathing, that usually helps.  i also periodically try to take a big exhalation and push out all the air in my lungs.  also, sometimes i find myself going faster than i should (i.e. right after a downhill slope, i maintain that speed on level ground).  when i remember to slow down, my breathing evens out.  like someone else mentioned, i also try and synchronize my breathing to my steps - it helps me make sure i am taking even breaths.  hope some of that was helpful, and good luck!