free will?

the notion of free will vs. determinism is another topic from class that freaks me out. Determinism basically says that there is no free will because everything is pre-determined because of previous events. If everything is already written to happen in a certain way, doesn't that mean that there is no free will? That we are pre-determined to do what were supposed to do? Doesn't that mean that we can't change what's going to happen? if there isn't free will then what's the point in doing anything? You can't change what's supposed to happen. Even if you would attempt to change your "destiny", how would you know what's supposed to happen in order to change it? Maybe it was already determined that you would try to change what you think was your pre-determined path.