My buddy Jake has been running marathons for the last three years. He started off with a respectable time of just under 4 hours and has lowered his personal best each time he's raced. He's done it the old fashioned way, hard work and a lot of miles.
Last Sunday he ran the Martian Half Marathon, with a goal of 1:30, 5 minutes better than his previous best. He ran a 1:30:39, finishing 50-something out of 1000-odd people, or in the top 5% of all finishers. You can read his account here.