One school of thought would be that I should answer thusly:
Sweetie, when I go running, most of the time, it's not a race. What I'm doing is improving my fitness, enjoying the fresh air, and relieving stress so I can be a better mommy. I do have goals, but instead of challenging someone else, I am really challenging myself. And with that, I am always a winner.
However, I prefer this approach:
I mean, come on: did you see anybody finish ahead of me?