What followed exceeded everyone's expectations - an amazing Olympic Games, followed by an equally amazing Paralympic Games. Six months on, the question is "What now?"
The strap line "inspire a generation" was spot on, but in many respects delivering that legacy is the most difficult of all the Olympic and Paralympic challenges.
The good news is that many agencies across all parts of sport in the UK are committed to make sure we don't lose this great opportunity.
I am involved with a charity called Join In, and the first step that we took last year was to capture that magical moment at the end of the Olympic Games when we anticipated that there would be unprecedented levels of excitement and interest in sport.
An idea was developed within London 2012 and funded with help from the Cabinet Office, resulting in 6,000 Join In events taking place between the Olympic and Paralympic Games, with over 300,000 people attending. We worked with the governing bodies of sport and their clubs, and crucially over 30,000 people made a commitment to volunteer in their club or community. Now we need to build on that.
Probably the most valuable assets in British sport are our volunteers. Without this incredible army of people, sport and clubs in this country would collapse and it is absolutely true to say that every member of Team GB and ParalympicsGB could trace the start they had in sport back to the volunteers in their clubs and community who inspired and guided them through those crucial early years.
This year Join In aims to be even bigger than in 2012, and the spirit of the Games Makers and other 2012 volunteers is central to what we are trying to achieve.
Our aim is for a summer of Join In running from the anniversary of the Olympic Opening Ceremony on July 27, through to the anniversary of the Paralympic Closing Ceremony on September 9.
During that period thousands of sports clubs and community organisations will open their doors again, attracting new participants and - crucially - also attracting new and different volunteers.
Our research shows that around 74 per cent of sports clubs say they need more volunteer help, but that help need not require a massive time commitment. People can volunteer even if they only have limited time available and work to their own strengths and interests through a huge variety of roles.
A lack of volunteers is a significant barrier to growing sports participation, and we hope that Join In 2013 will do its bit to help address that issue. So if you are a sports club or organisation interested in putting on an event, a Games Maker looking to stay involved or a potential new sports volunteer, take a look at our website www.joininuk.org and sign up. We'll keep in touch and let you know how you can be part of Join In 2013.
London 2012 was incredible for so many different reasons and the performance of Team GB and ParalympicsGB in both the Olympics and Paralympics was inspirational.
Now we need to take it back to where it all began for the athletes - to the clubs and communities, celebrating the volunteers who make sport happen and inspiring a new generation to give their time freely to help sport grow at all levels, across all communities in the UK.
Dave Moorcroft is the former world record holder for 5,000 metres. Following his retirement from elite competition, he served as UK Athletics chief executive from 1997 to 2007. He is now the director of sport for Join In. More information on Join in can be found by clicking here.