[anytime5704]

A friend of mine ran a marathon with 0 training in large part to spite me for laughing at him for saying he would.

Not as extreme as an ultra, but still an unimaginable feat for most people.

I wouldn’t have believed it if he didn’t wake me up to rub it in my face when he got back.

[jrs235]

I used to attempt things like that too (long races or tough mudders with little to no training). After doing my third tough mudder and getting injured I realized it's just stupid and a great way to cause a serious, possibly life enduring, injury.

[nradov]

Most people in somewhat reasonable shape could "run" a marathon on zero training. They might take 7 hours and have some minor injuries by the end, but they could finish.

[fwip]

To add a personal anecdote, I once walked 25 miles in about 8-9 hours* with a heavy bag, and then showered & walked to work afterwards. I was kind of out of it, but definitely not falling-down-tired or anything like that.

*I severely misjudged the length of the trip before setting out, thought it was about 5-6 miles.

[soulofmischief]

It must have been a nice day out.

[dghughes]

I'd say if you're under age 40 it should be possible unless you're in really poor shape but then again that shouldn't be a problem to get in shape.

As you get older recovery time is an issue it takes a long time to get over hard workout unless you've always done it but even so it's still not like when younger.

[SketchySeaBeast]

Wow. Could they walk the next day? That's seriously impressive.