Here's why it's hard to pinpoint the exact origin:
* Common Sense: The concept of encouraging someone to believe in their abilities is innate to human interaction.
* Many Variations: Similar phrases expressing confidence and motivation exist in many languages and cultures. For example, "You've got this!" or "Believe in yourself!"
* Informal Usage: The phrase "you can do it" is typically used in casual conversation, making it hard to trace its first recorded use.
While we can't definitively say who first uttered "you can do it," its widespread use highlights its timeless power as a motivational tool.