Atters, you can do it, I think it's just a matter of getting outdoors more often - ideally for your longer runs (if you do longer and shorter runs that is)
I used to struggle outdoors when I was used to the treddie, but it didn't take long at all to get used to it. Apparently, setting the treddie to a 1% incline is supposed to simulate the effect of running outdoors more effectively.
If you can run 5K indoors, you can outdoors, it's just a matter of getting used to it. And if you can run 5K, that's really not far off 5m, so you're nearly there already!!