@whitequark Let's suppose you had a habit of gambling or something like that. Let's suppose you know everything is predetermined. Let's suppose because of that, you change noting, and loose everything.
Let's suppose instead, you try to change anyway. The outcome may be a different if you are like this.
You see, it doesn't matter if things are pre-determined at all. The future follows from the past, and your belives are part of the path you are going to take.