London ( CNN ) -- Far from home , competing against the best in the world , with the eyes of billions of people on them , Olympic athletes are under the kind of pressure that few of us can imagine . But they 're only human and they have needs just like everyone else . Some of the world 's biggest sports stars from the past and the present told CNN what they just ca n't do without when they 're at the Olympics . Justin Gatlin , U.S. sprinter and 2012 100m bronze medal winner : . `` Communication with my son . I have a two-year-old boy and obviously he does n't know what 's going on now , the magnitude of it , but he knows that Daddy runs ... to hear him talk to me and tell me he loves me before I go out and compete , that gives me the mojo to go out there and do the best I can do . '' Michael Phelps , U.S. swimmer and winner of the most medals in Olympic history : . `` Cell phone . '' Elena Isinbaeva , Russian pole vaulter . World record holder and 2012 bronze medal winner : . `` People who support me and love me . '' Gabby Douglas , two-time gold medal winning U.S. gymnast : . `` My Bible . '' Jackie Joyner-Kersee , three-time gold medal winning U.S. athlete whose heptathlon world record has stood since 1988 : . `` This is probably a strange answer , but I 'm an asthmatic and I had to have my inhaler with me all the time because I was always afraid I might have an attack . The weather might change wherever I am so I kept it inside my sports bra . I could n't live without it . '' Ian Thorpe , five-time swimming gold medalist , the most golds of any Australian : . `` I actually had a bag of licorice that no matter how I felt , whether it was a good swim or bad swim , it was my go-to . So bizarre ... probably the worst thing to have as a thing at the Olympics . '' Felix Sanchez , two-time gold medal winning 400m hurdler , representing the Dominican Republic . Sanchez won gold in the 400m hurdles in 2004 , but as he was preparing to run his heat at the Beijing Olympics in 2008 , he learned his grandmother had died . He `` cried the whole day and ran terribly , '' he says , and did not qualify for the semi-finals . This year he ran with a photograph of himself and his grandmother tucked inside his running vest -- and regained his gold medal . `` I made a promise , '' he says . `` I wanted to win one more championship for her . '' CNN 's Caroline Paterson , Jo Shelley , Becky Anderson , Erin McLaughlin , Amanda Davies and Alex Thomas contributed to this report .
Michael Phelps said he ca n't do without his cell phone . 400 m hurdling gold medal winner Felix Sanchez carries a photo of his late grandmother . Ian Thorpe kept a pack of cigarettes handy . Jackie Joyner - Kersee , an asthmatic , tucked an inhaler into her sports bag just in case .