The cell games. Earth's most recent threat. Cell, some..maybe android-who knew what he was, but he came from the future, and was a threat nonetheless, decided to set up a little tournament of his own. Himself, versus earth's best heroes. Should all those heroes lose, that'd be it. He'd destroy Earth. This wasn't the first time Earth, the planet Goku was raised on, had been threatened. First it was Raditz, who'd found him, then kidnapped his son. Then came Vegeta and Nappa a year later, with the former having become his rival and...possibly a friend? He isn't sure quite yet. Then came having to go to Namek to gather those dragon balls, and having to stop a tyrant known as Frieza, who actually destroyed the planet. He was lucky to find an escape pod in time to get out before he was taken out too.
Then the androids, and the heart virus that kept him down. God, did his wife worry during that time. She didn't leave his side for a second. He found each threat stronger than the last, and as a saiyan, he loved the challenge, it made him want to keep getting stronger and stronger, to surpass his own limits.
But there was one issue. There was only a week to train before this competition. And Goku knew he wasn't gonna be able to beat Cell. But...he knew someone who would. Under just the right circumstances. And just who is the lucky one that had the ability to surpass even him, and beat this villain? Why, his own pride and joy of course! That's right, his own son, Gohan. Unfortunately....he's gotta tell his wife. And persuade her to let Gohan go with him to train, because she was very strict about the boys education. She wanted him to have brains too, not just brawn. And knowing her...hoo boy, he's gonna need luck if he's gonna get her to agree. And even if she did, which was just half the battle, he had to persuade Gohan to actually agree to enter too. And with Gohan being more on the pacifist side like him...he can only hope his son understands why he needs him to fight.
Goku was...smart in a fight. Never really killing anyone, but never using up more strength than he needed to, to conserve energy that he would possibky end up needing. He could come up with strategies the more he learned about his opponent. Just like any warrior. Thats what he was meant to be, a Saiyan warrior. And he technically was, since he'd been defending earth. But now, it was his son's turn to make his mark. At least in his eyes. And he knew Gohan could. His son had the potential. They just had to bring it out. And that'd start by getting him to unlock the super saiyan form he did.