Secret to immortality, what would you do if you found it?

Lets say hypothetically while you were trying to recreate a old family brownie receipe you stumbled on the secret to immortality. You realize this because you stopped aging while everyone else you know just got older and older. What would you do? Would you seek a patent and try to make a mint off the formula? Would you share what you know and share the brownies not the receipe with them to keep them young? Would you share all, and give them the receipe? Or would you tell no one and stay mum about it?