"No comprendo tus palabras."

I've been studying Spanish for a while, and people always seem to think I have wretched Spanish when talking about my running.

Here's an example of a conversation (which we would exchange in Spanish):

Random person: "Oh, you run. How nice. What do you run? Half-marathons?"

Me: "Oh, they're fun, but I like to run 50 mile, 100 mile races."

Random person: (Thinking to themselves) "She must be a complete dolt with her numbers." (Aloud) "5 miles?"

Me: "No, fifty. 100. I like to run really fun."

They're always baffled and then I start explaining all the times and distances and then it sinks it. But here's a complete opposite of that experience:

My Spanish teacher has long-understood that I run 50 mile, 100 mile races. I was telling her about a recent 50 miler I did and she was smiling. She asked if my boyfriend came to Florida to crew me in my race, and I said, "No, he had a race of his own." The following conversation transpired (in Spanish):

Spanish teacher: "How long was his race?"

Me: "One mile."

Spanish teacher: "How long? 100 miles?"

Me: "No. One mile. It's just a short race, on 5th Avenue."

Spanish teacher: "But...just one mile? That's it? Why would people want to run a race just that short?"

I had a good laugh at that one; apparently I have twisted my Spanish teacher so that she thinks 100 miles is normal, 1 mile is not.