Believing you can do something predicts whether you'll actually try

In 1977, psychologist Albert Bandura proposed that self-efficacy — your belief in your own ability to pull off a specific task — shapes which challenges you attempt, how much effort you invest, and how long you persist when it gets hard, often more than your actual skill level does.

— Albert Bandura, Self-Efficacy: Toward a Unifying Theory of Behavioral Change — Psychological Review, 1977