In "New Moon" Edward tells Bella that he doesn't want her to come with him when the Cullens move. He also asks her: "Please, don't be reckless. For Charlie's sake." After suffering for months Bella begins to pull herself back together by working with Jacob on motorcycles. She has discovered that anytime she tries something "reckless" she can hear Edward's voice.
Of course Bella is imagining this. Edward is many many miles away and he is not talking to her in reality, but she can hear him so she continues to try reckless activities to feel closer to Edward. She does everything from riding motorcycles to cliff diving. These are the only times she can feel close to him.
"One night, she discovers during an encounter with some dangerous strangers that she hears Edward’s voice in her head. Despite her fears, she begins seeking danger in order to hear him again."