The rest may have done him good. By the time he finished running, early on January 1, Keith had also smashed the Irish 48-hour and 72-hour records. He had reached his target of 300 miles (482.8km) after 67 hours 21 minutes and decided to stop.
Before this year's race, only two other men had claimed the gold buckle awarded for those who clocked up 300 miles or more. One was the course record-holder and ultra-running legend Yianis Kuoros of Greece, who ran 323 miles in 2005 and the other, John Geesler of the US, with 300.122 in 2004.
The best Irish performance came from World Jogger Tony Mangan, who ran 279 miles to finish second behind Geesler in 2006 and won the race a year later.
All was to change in this year's race. American Joe Fejes, race winner in 2011 with a total of 280.3 miles, was a man on a mission. From the start of the race, he set what many observers felt was a suicidal pace on the specially designed mile loop at the Camelback Ranch. After nine hours, interrupted only by short rests for food and drink, Keith, who had run a very respectable 84.5 kilometres, was already 10km behind the flying American Fejes.
At 25 hours, Keith, with more than 209.5km to his credit, was now 22km behind Fejes and 17km ahead of third-placed Ed Ettinghausen.
Day two proved tougher, with the early pace taking its toll and both men slowing down, although Keith's distance of 342.969km was a new Irish 48-hour record. On the third day, Keith found a new lease of life and managed to cover an additional 100 miles in 20 hours to reach his 300 mile target.
Ahead of him, Fejes had smashed the course record with a total of 329.64 miles (530.5km).
The first man to congratulate the Irishman was Mangan, who had met Keith over the Christmas break and given him valuable advice.
After a much-needed break in Dublin over the holidays, Mangan has resumed his World Jog and is currently in Fiji.