In a little over 100 days, the “Greatest Show on Earth” comes to London.

David Roberts joins 5,000 runners given a sneak preview of what is in store at the 2012 Olympics

AS a journalist, you are taught to avoid cliches whenever possible. But shivers down my spine is the only way to describe the emotion of entering the Olympic stadium to the strains of the theme to the film Chariots of Fire. It’s a moment I won’t forget.

Prior to taking part in the National Lottery Olympic Park Run, I was somewhat cynical about the Olympics.

However, when you enter the Olympic Park, it is difficult not to be moved by its sheer grandeur.

I was lucky enough to be one of 5,000 runners – from a ballot of 40,000 – to take part in the National Lottery Olympic Park Run.

The five-mile race wound through the park and past the majority of venues, which hitherto had existed only as artists’ impressions in my mind.

Apart from the runners, the park was eerily empty and it was a unique experience to see it in pristine condition before the hordes of spectators arrive.

The race itself was a goodnatured affair, with the majority of runners using it as a sightseeing tour, rather than an opportunity to beat personal bests. That’s my excuse anyhow.

It was not unusual to see a runner pull up to take a picture of themselves in front of one of the venues.

There was a smattering of celebrities too. Princess Beatrice started the race and completed it, along with Sporty Spice Melanie Chisholm.

Brendan Foster, an Olympic bronze medal winner and founder of the Great North Run, was also present.

He said: “It’s amazing to see so many people from the North-East able to take part in this unique national event.”

Dianne Thompson, group chief executive officer of National Lottery operator Camelot, said: “It’s the first time in Olympics Games history that the public have been given the chance to take part in an event like this.”

We raced past the velodrome, the Copper Box handball, fencing and goalball venue and the basketball arena, where I will be lucky enough to watch the men’s handball in the summer.

Finally, the route took me through the main stadium’s undercroft, before I finally burst out into the sunlight onto the running track where the world’s elite athletes will compete.

After five miles, I was tiring.

But is was impossible not to pick up the pace for the final few hundred metres.

Even partially full, the stadium was an amazing spectacle.

When it is at full capacity, it will be awe-inspiring.

I crossed the finish line in a distinctly average time of 44 minutes, but the race itself was anything but. I lingered as long as I could on the trackside, doing my stretches, before heading to the stands.

In years to come, I can legitimately tell my children and grandchildren that I crossed the finish line at the Olympic stadium before Usain Bolt.