 Jim AbrahamsSelf - Father / Founder, Charlie Foundation / Filmmaker | Self - Father / Founder, Charlie Foundation / Filmmaker |
 Vinnie TortorichSelf - Narrator / Producer / Trainer / Author | Self - Narrator / Producer / Trainer / Author |
 Bret ScherSelf - Cardiologist | Self - Cardiologist |
 Gary TaubesSelf - Journalist / Author | Self - Journalist / Author |
| DDave FeldmanSelf - Software Engineer | Self - Software Engineer |
 Eric WestmanSelf - Internal Medicine Doctor | Self - Internal Medicine Doctor |
| AAndreas EenfeldtSelf - Physician | Self - Physician |
 Drew PinskySelf - Physician | Self - Physician |
 Georgia EdeSelf - Psychiatrist | Self - Psychiatrist |
| NNina TeicholzSelf - Journalist | Self - Journalist |
| VVilhjalmur StefanssonSelf - Explorer (archive footage) | Self - Explorer (archive footage) |
| IIvor CumminsSelf - Biochemical Engineer | Self - Biochemical Engineer |
| AAncel KeysSelf (archive footage) | Self (archive footage) |
 Jeffry GerberSelf - Physician | Self - Physician |
 George McGovernSelf - Politician (archive footage) | Self - Politician (archive footage) |
| GGary FetkeSelf - Orthopaedic Surgeon | Self - Orthopaedic Surgeon |
