You watch Usain Bolt smash his own 100m world record in 9.69 and start to celebrate 10m from the end.
You watch Michael Phelps collect his seventh gold medal and know he is just going to get his eighth tomorrow.
Then you see the glint in Bolt's eye as he poses in front of the Jamaican fans, and hear Phelps say 'I don't believe anything is impossible, if you really want it.'
Visualise it. Execute it. Just like Philippe Petit did, in August 1974, when he walked the tightrope between the Twin Towers of the World Trade Center in NYC.
These guys truly walk on air.