A world and Olympic 5,000m and 10,000m champion deserves to be taken very seriously, whatever their next athletic aim, because they have earned the right to set big goals.
And so it is with Mo Farah, who is believed to be aiming to become the first man in history to break the fabled two-hour mark for the marathon.
He is yet to prove himself at the distance, but given his achievements on the track - where he has accomplished everything he could have dreamed of - he every reason to aim incredibly high in his new pursuit.
It may sound like just another goal for an incredibly driven and focused athlete, but this really would be something stupendously special. Genuinely epic. A feat that would write his name in the history books for the rest of time.
To be the first human to go under two hours for running 26.2 miles is not something to be taken lightly. It's akin to trying to be the first 100m runner to go under 9.5 seconds, or a high jumper clearing 2.5m.
Wilson Kipsang was hailed for "smashing" the world record for the distance when he took 15 seconds off it in Berlin last Sunday. What Farah is hoping to achieve is far, far beyond usurping the 31-year-old Kenyan, however.
Kipsang's time was truly remarkable, but the 30-year-old Farah would have to go much, much further if he is to break the two-hour barrier. Indeed, he would have to run just over three minutes and 23 seconds faster.
The 15 seconds Kipsang took off the previous world record, set by compatriot Patrick Makau two years ago, was a hefty chunk to take off the best ever before recorded. For Farah to take nearly a further three-and-a-half minutes off that mark initially seems almost inconceivable.
To put that in context, it took over 25 years for three and a half minutes to be shaved off the record between Belayneh Dinsamo running 2:06.50 in April 1988 and Kipsang running 2:03.23 last month. For Farah to take the same amount again off the record between now and the end of his career seems inconceivable.
But then this is no average runner; no standard athlete. This is a man who, under the guidance of distance-running guru Alberto Salazar, believes that he can take the sport of athletics to a new level with his personal feats.
Salazar, let us not forget, is a former marathon superstar himself. There can be no more ideal coach to mastermind Farah's pursuit of the marathon-running holy grail.
And despite the generally slow progression of the record, there is precedent for such a major jump. English-born Australian runner Derek Clayton trimmed an astonishing three minutes 27 seconds off the marathon world record with two runs in 1967 and 1969 - despite the previous record having only been set in 1965.
Farah himself does not lack any self-belief, and nor should he. What he has already achieved in athletics amounts to a simply spectacular CV. At the age of 30 his career has been naturally progressing to this new challenge.
As Sir Roger Bannister rightly said when asked by BBC Radio Five Live about the possibility of Farah's tilt at the world record, "Mo is the most talented, wide-ranging distance runner we have ever seen. I don't think Mo will be ready to do it next year, but it is of course possible."
Farah has yet to run at the marathon distance, but his credentials are undoubted and his determination and ambition cannot be overestimated. Which is just as well, because what he would be aiming to achieve is hard to fully grasp.
Lord Sebastian Coe's assessment put it in perspective: "This is a very ambitious aim from Mo. Go down to your local running track, run a lap in under 70 seconds, and then continue for 105 laps - you get the scale of what we are talking about."
"The arithmetic of a sub two hour marathon is both instructive and quite sobering. You've got to run four minutes, 35 seconds per mile over the course. This is highly ambitious observation from Mo but he has the right training group in his corner. This is a very, very ambitious aim."
Bannister added: "It has to be a set occasion, it couldn't be at an event and he would have to be lucky to have a day when the weather is favourable.
"He needs a course that is relatively flat, without hills. He needs a freedom from wind because that slows you down and he has to have pacemakers who will enable him to relax."
Farah already has a wonderful legacy in place following his spectacular achievements at the last Olympic Games and World Championships, but it would be a gross mistake to believe that we've already seen his best moments.
Breaking the two-hour mark for the marathon would take Farah to new levels of heroism. His greatest accomplishment could very well be ahead of him.