I've run one ultra race and numerous non-race "ultras" - if it's not a race, it's just a long run right? triumph07: that depends on a bunch of factors - ultras can be anywhere from 42.3km to 200km+, can be flat or extremely hilly, smooth road or trails that require clambering - the usual guide is that if you can complete a marathon, you can complete an ultra. How fast however is another question...
Long distance running is a very similar thing to frugality/Mustachianism imo, they both require a certain mindset, flexibility, not only surviving but finding comfort in situations others don't want to even try. In both things, once you try the 'harder' option, you often find it's the most enjoyable. Not to mention a pretty cheap hobby!