Your active protag needs three things: a goal, a plan and a flaw.
The goal: win the prize, save the planet, find the killer. How will he get there? He will drive the bus there. The plan is the bus.
His flaw is that he is the world’s worst bus driver.
A passive protag gets on the bus and sits down and looks out the window. He sees things, someone sits down next to him and strikes up a conversation. Someone else is a little wacky. There’s a girl he likes. He gets her number. Maybe the bus breaks down and he doesn’t have money for a cab so he walks. He eventually gets where he’s going.
Make him drive the bus.