why do i feel like the older i get the more sick of school i become and im starting not to care?

Question

Like im just tired of it or somthing. Im a senior in HS but doing my first year of college. I just want a break and im sick of deadlines and due dates and i feel like i dont really care anymore. I dont understand why? i used to be the model student, they type that would be close to tears if i go an F so why this now when im at the most imporant time in my education? why it actually is starting to count.