Lord Coe has said there is still a lot of work to do to prepare for the Olympics, but he is confident and happy with how preparations are going.
He said there will be no last minute rush, and that he is very proud of how hard his teams have worked to keep everything on track.
A British businessman spends around £500,000 a year on funding young athletes from the UK.
After years of planning and preparation, there are just 100 days to go. Today, a series of events will mark the special occasion.