✔ 最佳答案
"So I took the job as a sanitation worker. I didn't just ride in the trucks now".
What it's saying is, "So I took the job as a sanitation worker. Before I became employed as a sanitation worker, I used to just hitch rides or get free rides in the trucks for fun and sport; now I'm riding in the trucks for a legitimate reason; I'm a sanitation worker."
"I didn't just ride in the trucks now." That says the same thing in short hand, with "now" referring back to and refuting the idea that the author is still just riding in the trucks". Now he has a job to do.
Hope that helps.