So you've always liked the idea of running a marathon but the problem is you don't really have the time (or desire) to train for a full marathon. It's OK, marathon running is for a specific type of person, so don't worry if you're not eager to run 26 miles in one day. How about running a marathon in a week or so?
Instead of running the full 26 miles in one day, break it up into segments. When you've completed 26 miles total, give yourself a small reward. If you run about 3 miles each time you run, you'll have completed your marathon in 8 days—not too shabby, eh? If you've gotten a nice prize for yourself once you've completed 26 miles, you may be motivated to try to increase your endurance and run more miles in one day. Before you know it, you'll be running ultramarathons, in segments, of course.