He has a silver and bronze as consolation, and world titles to cherish from outdoors and inside. Yet, even at the age of 39, he is intent on defending his crown in March's world indoor championships in Poland. Retirement can wait, the Kenyan-born American confirms. In racing, you are a long time dead.
The evergreen and ever-ready competitor will captain the USA in today's Indoor International in Glasgow with points to prove only to himself. "You think: 'what else can I do?' I'm motivated by that because my work ethic is still the same," he explained. "I still train well. I still take care of my body. I eat well. So I ask: 'what am I lacking?'
"Sometimes I get motivated by running with the young guys. I think if I can get a record, can I beat them? When I train now, I have to do the best I can because the young guys are faster and stronger. So let me put myself in there and see what I can do."
At the Emirates Arena, where he will run the 3000m, his opponents - including Scotland's Mark Mitchell - are a decade younger and then some. However, since Lagat switched allegiance from his birthplace to the USA 10 years ago, he has become a figurehead for an emergent group of middle-distance specialists.
In a land of immigrants, there was no carping that he was stealing away a spot. "Nobody had any issues," he recounted. "The only slight problem was that Kenyan friends and fans felt they were losing one of the guys who were strongest, because in 2004 I was ranked number one in the world. The news that I became a [US] citizen was rough but on the other hand, they appreciated what I had done for the country since I won the World University Games. The reaction was positive on both sides."
Glasgow, he hopes, will be a springboard towards one more world gold in the colours of Uncle Sam. "I heard Mo Farah is training for the marathon so that's one less to worry about," he added, with a smile. "But I know it's going to be tough. For me, that's my motivation. How is it going to look like if I go in there as a 39-year-old and win that again?"
Meanwhile, Kim Collins, two years Lagat's junior, has revealed a regime change in the St Kitts Federation could pave the way for the ex-world 100m champion to compete in the Commonwealth Games. Collins had been barred from representing his country after being sent home from 2012 Olympics but signalled talks to bring him back are at an advanced stage.
The 2002 champion said: "At this stage, it's about competing and being able to compete effectively. You don't want to come and get thrown out in the first or second round - you want to be a real contender."