I am a little surprised by Haile Gebrselassie's decision to retire but he will be remembered as one of the great distance runners and I don't think anyone will achieve as much as he did.
He was a great champion, a great racer, but what set him apart was his range, from 1,500m - where he ran particularly fast indoors - to the marathon.
Haile was good on the road, good at cross country, he was double Olympic champion on the track, had numerous world titles and goodness knows how many world records he set.
It's difficult to explain how big a star he is in Ethiopia. You've got to think David Beckham but bigger. If he wanted to become the president or prime minister he could easily do it
Ethiopian compatriot Kenenisa Bekele is meant to be the guy who will follow in his footsteps but he has got a long way to go to tick all the boxes Haile did.
I saw Haile at the Great North Run in September and he was talking about London 2012. He was still full of enthusiasm, so something has obviously happened in the last month or two to change his thinking.
You do reach a point in your career when frustration gets to you and you think 'right, that's it'. Because Haile is such a competitor and such a great man, he only wants to give his best.
I just hope he has not made a knee-jerk decision and that retirement is something he has been thinking about over a period of time.
Haile has had some real tussles over the years and did not always win his races easily.
Gebrselassie celebrates winning the men's 10,000m Olympic gold in 2000
He had a great finish but was not unbeatable. He came up against some formidable athletes during his career and always managed to dig deep on the big occasions when it mattered.
The 10,000m at the 2000 Olympics in Sydney, when he battled to the line with Paul Tergat, was one of the all-time great races. The winning margin was one you would expect in a 100m not a 10,000m.
I was not commentating on that race so I was able to enjoy it. The tension was building throughout. It was phenomenal and I remember thinking 'oh, he's lost this' at one stage.
When they crossed the line, I had to look at the monitors to see who won because I could not really tell, they were neck and neck.
Haile's appetite for breaking records was immense.
One of the more recent ones he broke was the one-hour mark on the track. It is a daft record but he had a go because he just had this desire. He had no fear.
CRAM'S TOP GEBRSELASSIE MOMENTS
Sydney 2000 - 10,000m Olympic gold
Zurich 1997 - 5,000m world record
Berlin 2008 - Marathon world record
When he moved up to the marathon, a lot of people said he would not succeed. His first couple of attempts were not great either.
He struggled in London and everyone said his running action was not suited to the distance, that he had this bouncy style that was not economical enough. But he proved a lot of people wrong.
It is a bit of a shame he has packed it in now because I do not think his world record for the marathon of 2:03:59, which he ran in Berlin in 2008, will last that long and he definitely could have run faster.
I am a bit biased but for Haile to achieve success in such a number of events is phenomenal.
People flag up the fact that 'so and so won both the 100m and 200m' but it is still sprinting at the end of the day. Yet the difference between the 5,000m and the marathon is massive. They are completely different events and the marathon requires a completely different mindset.
If you look at someone like Paula Radcliffe, she was pretty good on the track but could not win the 5,000m or 10,000m at the World Championships or Olympics. Other people are very much the same but Halle could do it all.
Gebrselassie broke the men's marathon world record in 2008
It was like speaking to an 18-year-old kid just starting out whenever you chatted with him. He was a great person to be around, particularly for athletes, because he was incredibly enthusiastic. Sport needs people like that.
We are a bit parochial sometimes here in Britain and we do not always treat the achievements of foreign athletes in the way that we should.
Haile understood that there was a big world outside of Ethiopia. He learnt English, was happy to do interviews and always went around with a big smile on his face. Even his grimace when he was running came across as a big smile!
People would say 'oh, he's even smiling during the race' but he wasn't, he was grimacing. On and off the track, Haile looked as though he was enjoying himself.
World Championships, Stuttgart 1993 - Wins 10,000m gold (aged 20)
Atlanta Olympics 1996 - Captures 10,000m gold
Hengelo, Netherlands, 1998 - Breaks 10,000m world record
Helsinki 1998 - Breaks 5,000m world record
Sydney Olympics 2000 - Wins 10,000m gold
Arizona 2006 - Breaks half marathon world record
Berlin 2008 - Sets new marathon world record
I have been to his house in Ethiopia and it is difficult to explain how big a star he is out there. Think David Beckham but bigger. If Haile wanted to become the president or prime minister, he could easily do it - and maybe that is something he will do.
He is also a successful businessman, has incredible influence in the country - both within and outside of sport - and has done all sorts of great things away from the track.
I was in Ethiopia during the Great Ethiopian Run a few years ago and there were 15,000 to 20,000 people in the national square in Addis Ababa to compete.
There was a false start and 5,000 people went hurtling off. It was a bit chaotic, there were announcements, even the police got involved, but people did not start to listen until Haile got up on the rostrum with a loud speaker. He was even telling the police what to do!
Haile loves his country and wants better things for the people there. After travelling the world and seeing how things are done elsewhere, he gets a little bit frustrated at times that things are not like that at home. He is very keen to try to make positive changes.
He is an iconic figure in his homeland and it will be interesting to see what he does next.
Steve Cram was talking to BBC Sport's Aimee Lewis.
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