I'm poor, and need a wedding gift. How about the head of a dead thing as far away as possible?
Refusal to Action
Maybe, just maybe this isn't the best idea. But what do I know, I'm a Greek myth from forever ago.
Persues was born in a bronze house underground, by Danae and Zeus.
Meeting the Mentor
One day, in attempt to end Perseus, Polydectes lied to Perseus by telling him that he was too poor to get a wedding gift for 'his upcoming wedding'. Perseus agreed reluctantly.
Crossing the Threshold
Perseus has a little bit of logic, and thinks that maybe killing a giant Gordon isn't the best, or safest idea out there.
Allies, enemies, and tests
As Perseus was in doubt, some nosy gods came from the sky. The goddess Athena and the god Hermes. They're pretty much consorts throughout the rest of the story. They also gave him a indestructible sword, a mirror, a wallet, sandals, and a cape.
Then, Perseus, Athena, and Hermes all set off on a semi-giant quest to kill Medusa in Polydectes' favor.
Finally, Perseus ventured forth to tackle medusa. And eventually kill his grandpa with a frisbee.