The 39-year-old Kenyan-American, a 13-time world and Olympic medallist (five of them gold), has sailed serenely beyond most challenges faced during his illustrious career but his memories of the 2013 New York half marathon aren't quite so rosy.
He came in 12th, in a time of 62:33, yet completed the race with an abiding feeling that the finishing line had arrived just in time, and had there been another few steps, he might not have made it. Consequently, he has had little compulsion to endure such longer distances again. And with Farah apparently having concluded likewise after finishing eighth on his London Marathon debut in April, Lagat will be delighted to welcome the Londoner back to the track at the Sainsbury's Grand Prix at Hampden Park next month.
"After that half marathon in New York, I realised at the end of the race that, you know what, this thing is different," said Lagat. "I could not go one metre more. Then you think about a guy doubling what I did. The marathon is a different animal.
"I spoke to Mo on the phone after he came back from London to Portland and I said to him 'what you did was amazing, seriously amazing', because he is a 5000m/10,000m guy and he stepped up right to the big one. I met him also at the Prefontaine classic [a recent event in Eugene, Oregon] and we had a chat about it. He acknowledged that it was tough and the way he put it was that he didn't think that was for him now, and he was looking forward to coming back to the track.
"For me I am excited that he is coming back. Sometimes people start leaving early, and doing something else, but I like competing against him, I want him to stay longer. It was like when Hicham El Guerrouj retired. I asked him 'why are you leaving me'?"
The veteran, who finished fourth behind Farah in the 5000m at the London Olympics in 2012, despite being tripped by Isiah Koech at a crucial moment, will compete in the 5000m in Glasgow on July 11/12, with Farah likely to run the two-mile or 3000m.
He enthuses about the freshly-laid Hampden track - envisaging a Scottish variant on Zurich's atmospheric Weltklasse - even as storms lash the south of Glasgow, but it is a source of regret that he won't be back at the venue later that month for the Commonwealth Games.
Lagat was actually selected for the Kenyan team for Manchester in 2002, but chose to attend the African Games instead, and had become a naturalised US citizen when the Games reached Melbourne in 2006.
"My chances were in Manchester in 2002 but I missed that one," he said. "I thought I was smart ... but I wasn't."
Thankfully for Glasgow 2014 organisers, Farah has now pledged to appear, and it is understood he will double up in the 5000m and 10,000m, just as he did at London 2012. While that prospect would surely please Team England, who will be keen to maximise guaranteed gold medals, Lagat sees no reason why he could not also have a future at 1500m, the distance in which Farah broke Steve Cram's 28-year British record last summer.
"One thing that goes for him is that he is still young, he is not 39 like myself," said Lagat. "It is easier to recover more quickly when you are young. Training accumulates in your body and you can never lose it. He doesn't need to panic. He is approaching the Commonwealth Games in a smart way now, because we haven't seen him racing yet.
"April was the marathon in London, now two months have gone, and he is getting back into shape. All he has to do now is get in some training, which is not as intense as the marathon training, and sharpen up in July, and he will be ready to go."
Farah avoiding the 1500m would at least clear the path for an alternative home favourite. Last season saw Chris O'Hare, the 23-year-old from West Linton who has spent the last four years at Tulsa University competing on the collegiate athletics circuit, set a personal best of 3.35.37 for the 1500m and reach the final of the World Championships in Moscow. Lagat knows O'Hare well, indeed he did a work-out with him prior to the Sainsbury's Indoor Grand Prix in March. He feels a home medal at Hampden Park shouldn't be discounted, even if the Scot is currently sweating over a hamstring injury.
"There are a lot of athletes who may be better than him in terms of talent, but he is a fierce, courageous athlete," said Lagat. "These character- istics are awesome for a young athlete. You need people who are not afraid to run even against guys like Asbel Kiprop [the Kenyan double world championship gold medallist] and Chris is a kid that actually can do that. When I was running 1500m I used to be careful about these types of people because I knew how dangerous they could be. He is at home, so he will be one of the hardest guys to beat and I think he can win a medal.
"When it is tactical sometimes the best athletes lose, and you get someone who is right in the middle and can handle the fast pace and the slower pace.
"If I was in Chris's camp, I would tell him to be comfortable in both races. If it comes to a kick then yes he can handle it. If it is hard, then he has to handle that too. All he has do is come in with guts, with the belief he can handle the guys, that he is not afraid of them."
As for Lagat himself, after indoor World Championship silver in the 3000m in Sopot, Poland, in March, the double world champion has not been delighted with his early outdoors form, but he knows his body well enough not to panic after the odd disappointing time or two. With a European base camp at Tubingen in Germany, he is targeting next year's World Championships in Beijing, and is speaking "hypothetically" about mounting a quest for an elusive Olympic gold in Rio in 2016, by which time he will be nearing 42.
He puts his longevity as an athlete down to a lifestyle which sees him use no supplements, but eat well (his wife Gladys is a registered dietician), and enjoy the odd game of golf and even an occasional glass of red wine. There may be more time to enjoy the good things in life but thankfully age has been unable to slow Lagat down.
o Watch the world's best athletes including Yohan Blake, Mo Farah, Christine Ohuruogu and David Weir at the Sainsbury's Glasgow Grand Prix on July 11-12. Tickets via britishathletics.org.uk