Sigh...I get these so often... And if you've ever even attempted a race longer than a marathon, I know you've gotten them too. It's not their fault they don't understand the ultra sickness. Here's an article to toss their way to help clear up any misconceptions.
Q.) 100 Miles? Did you know I don't even like to drive that far?
A.) We did know that. We've actually known it since the dawn of ultramarathon time, way back when we first told our mothers that we were attempting something so ridiculously stupid. We also understand that this is the token way of clearing the awkwardness, and masking what you're truly thinking. Things like "Why??? Just...Why?" and "My gosh, what a freaking idiot." We may seem annoyed, but we actually do appreciate you sticking to the code...
"Oh, you're running 31 miles? I don't even like to drive that far!"
"Oh, you're running 50 miles? I don't even like to drive that far!"
"100 miles? Wow. I don't even want to drive that far!"
"Oh, you're running 26.2 miles? .......Cool. My dentist did that. So did Oprah!"
Q.) Isn't that bad for your knees?
A.)At one point, we would have vehemently debated you that "NO, THIS IS NOT BAD FOR MY KNEES!", and that you have absolutely no idea about anything, at all. But... that all changed after many of us ran 100 miles--with half of it down mountainsides covered in rocks--It was at that point that we decided that YES, it is indeed very bad for your knees--probably the worst thing ever. And oh my gosh, my knees hurt thinking about it. However, we won't tell you that. Instead, you'll get a cliche line about having good memories when we're 80. End of discussion.
Q.) Have you ever read Born to Run?
A.) Seriously? This again. I.. I just.. Next question.
Q.) How do you.. like..eat and stuff?
A.) Everyone's different here, but for the most part, WHILE we run, we eat/ drink things closely resembling things familiar to you like Gatorade, baby food, and fruit snacks. See, we run for a stretch, suffer and complain to ourselves and eat the things out of our little backpacks (..they're actually hydration packs, different story). All the while trying to make our way to special tables of delicious food set up in the wilderness manned by gracious Enablers of the Ultras. These tables happen every 5-10 miles Basically, you're probably thinking something like this:

But, it's actually more like this:

The goal is to move extremely quickly through The Tables of Temptation, so as not to become too familiar with life before running the ultra.
Q.)...^^^and stuff?
A.) Yeah.. this time it IS exactly what you're thinking. This is really awkward. Moving on.
Q.) Oh, my friend actually ran an ultra before. 200 miles! I think the race was called the Ragnar?
A.) Please forgive us when we appear to become hostile while passionately slamming down the fact that "NO, your friend did not run 200 miles. Your friend ran 6 miles and slept in a van." Understand that we do not think any less of your friend. We in fact envy him for having the brains and the decency to set fun attainable and realistic goals. We just need you to understand that we are insanely dumb..and stubborn optimistic enough to attempt the whole 200 with our own two feet. Furthermore, we do not run relays, use the word relay, think the word relay, or speak the word relay. Ever.... "But, anyway, which Ragnar was it?"
Q.) Do you sleep?
A.) There are a few of us who have perfected the art of walking while sleeping. We refer to it as "death marching". But for the most part, we typically try to stay awake the duration of the entire race. Yes, for us slow folks, this can be more than 30 hours of wakefulness, and often induces things like hallucinations of trains, kids holding pumpkins, and Captain Jack Sparrow. No big deal in the grand scheme of things.
Q.) .....These sound terrible for you.
A.) Sigh... we admit defeat here. We used to battle it like the knee thing, but, then we felt the aftereffects of things like 100 miles on pavement. We eventually decided someone around mile 80 that, "My gosh, forget natural childbirth, this is hands down the worst thing I have EVER done to my body." Yes. It is absolutely atrocious for us. We know this. And really, anyone who tries to deny it either hasn't finished a 100 yet, is on crack, or is just a total fraud. All we can do here is hope that you will listen to us preach the therapy gospels of just how incredible a 100 is for the mind... please?
Q.) So...Did you win?
A.) Unless our name is Kilian, Rob, Anna or Emelie or something slick like that, we just smile and laugh and nod our heads. Because no.....and try to ignore your deeply wounding, gut wrenching question that struck us to our very cores. Pondering things like, "I won my age group in a 5k once." And "My kids think I'm really cool...but how long until they know the truth?"
Q.) I thought after the last time you ran 100 miles, you said you were never doing it again. Why are you signed up for another one?
A. We expect any and all persons to honor the unspoken code: ignore and forget all things verbalized during an ultra, 24 hours after an ultra, and up to 3 months post ultra--Depending on the severity of the distance, weather, and terrain of the race.
Q.) Cool. 100 miles? So have you ever done a marathon?
A. Really there's no polite answer to this.

Thanks for reading, guys! :) Have an awesome day, and happy trails! ~Ash