After John Lennon’s death, Yoko Ono found it hard to smile, but she tried to smile for her health. Now she has launched the #smilesfilm iPhone app for people around the world to upload and view pictures of themselves and other people smiling. Her advice to grim-faced folks: ‘Look at yourself in the mirror and force a smile. It is just awkward at first. But after you keep trying it every morning, one day you will start giving your smile to your whole body … and then giving your smile to people with emotion’.