I had a really hard time with this, but I think that it comes with time...just takes a little getting used to. The only real tip I have is to try to run on asphalt rather than concrete(a little easier on the knees)...and just find an area that you enjoy! It is the perfect time of year to start running outdoors. So good luck and have fun, hopefully others will have more advice!

I am in the process of doing this, too! I can do 5k easily on a TM, not so easily outside.

I'm doing unstructured intervals... that is, running until I need to take a walk break, recovering and then running again, repeating as many times as I need to until I make it to the end of my distance goal for the day. I'm noticing improvements - that is, I'm taking fewer and fewer walk breaks. (Except today of course. Crappy run today!)

Good luck!