How do I know if I have product-market fit?

Signs of product-market fit: customers seek you out (not just respond to outreach), retention is strong, users recommend you unprompted, and growth feels organic. Sean Ellis's survey asks users how they'd feel if they couldn't use your product—if 40%+ say 'very disappointed,' you likely have fit. Before fit, everything feels like pushing a boulder uphill. After fit, you're pulled by demand.