Mr. Shou Lao became immortal by the following. He was told by a fortune teller to enter a field with a packed lunch, for he was doomed to die at 19. When he arrived there, he found two men playing checkers, who turned out to be the gods of Birth and Death. He silently offered them food, and after they had eaten it they decided to give him the gift of immortality.
I think he’s pretty lucky. All he did was pack a lunch and he received immortality.
A person is doomed to die in a battle against 6 polar bears. He is scared, and before he enters the wilderness to fight them, he prays to Shou Lao for long life. When this man enters the battle Shou Lao protects him from all harm from the polar bears so that he may successfully defeat them.