London 2012 organisers launched the slogan 'Inspire a generation' to mark 100 days to go to the start of the Olympics.
A launch event at Kew Gardens in London also saw the unveiling of giant Olympic rings created by flowers which will be visible from flights arriving at Heathrow airport.
Organisers also announced the RAF aerobatics team the Red Arrows will perform flypasts across the UK to mark the opening ceremony on July 27, passing over Olympic 'live sites' in Belfast, Cardiff, Edinburgh and London.
There will be a total of 22 live sites in towns and cities with big screens.
London 2012 chairman Sebastian Coe told a news conference at Kew Gardens: "I am delighted to announce the motto 'Inspire a generation'.
"It is everything we have been saying since we have started this extraordinary journey, not just since we got across the finish line in Singapore.
"It is the heartbeat, the very DNA of this organisation and a rallying cry for the athletes to come to the UK to perform at their very best and inspire the world."
Coe said it was vital that organisers put athletes at the centre of the preparations and made sure they were allowed to perform to the best of their abilities.
He added: "We have an obligation to get these Games right for our competitors.
"I say to my team that every time you see a young competitor, Olympic or Paralympian, taking their place in a venue, they will have devoted half their lives to getting there.
"We can never allow them to be a victim of our shortcomings."
The organisation of the Games has been relatively untroubled with all the building work coming in on time and within budget.
London 2012 chief executive Paul Deighton said organisers would be "paranoid" in ensuring complacency did not creep in during the final days.
Deighton said: "It is vital the smoothness of the preparation is reflected in a spectacular outcome otherwise it doesn't amount to much.
"When it comes to the risk of complacency I can assure you in life these days only the paranoid succeed so there is absolutely no danger of us not looking at every risk that would prevent us delivering these Games in the effective and spectacular way we have promised."
IOC president Jacques Rogge said expectations were high but he was confident that London would deliver.
Rogge said: "Organising the Olympics is a team effort and over the next hundred days, people from all walks of life and from all around the world will play their part in helping to make London 2012 a Games that will inspire a generation.
"From the athletes refining their technique, to the volunteers learning about their roles, to the torchbearers carrying the Olympic flame and the people supporting them as they go, each and every one of them is playing their part in making these a Games to remember.
"Around the world, the excitement is growing and expectations are high but I am confident that Britain and London will deliver a great sporting event and a warm welcome too."
It was also announced today that 40 'Coubertin Oaks' trees are being planted at venues around the UK.
The trees will be grown from acorns taken from an oak planted in 1890 during the visit of the founder of the modern Olympic Movement, Pierre de Coubertin, to the Wenlock Olympian Games.
The first oak was planted by Coe at Kew Gardens this morning. Others will be planted at William Brookes School in Much Wenlock, Shropshire, the Forestry Commission's National Arboretum, and at the UPS London Central Centre in Camden.
what do you think?
Lets hope it does inspure a generation rather than enslave a generation with the debt. I for one will raise a glass of coke and eat a maccies burger to this pinnacle of health and fitness.
Havnt met a single person who is actualy looking forward to this, country in a right mess, yet no expense spared for this little lot! Enlighten me?
It's called "WHO CARES" we are bankrupt. But while Rome is burning the show still must go on!! :o(
Methinks thus: The generation they are attempting to inspire, could have, themselves, invented a better and more apt slogan.
"Inspire a generation" to do without a pension to pay for this farce