Destiny or foretelling?

Do you think these words could go together? The more I think about it, the more confused I become :(

Some people do believe in Destiny. They believe something is going to happen, as it is their destiny. Some people do believe in predicting the future. They also believe in doing some things to change their predicted future.

If I say this thing is going to happen, as it is my destiny, then how can I rectify it by doing anything? If I can modify it by doing something, how could it be the destiny? If I am destined to do something, will I do it no matter how I act in the process of doing that thing?

Predicting future looks like if-else conditional statements to me (w.r.t. programming)If I do this, something will happen. Else something else will happen. And the nesting of such ifs and else continues… Who controls the path? If we chose the path, then its like saying we chose our destiny, which doesn’t make sense according to meaning of destiny. If WE don’t chose the path, and if we are forced to make a selection, then it doesn’t make sense with respect to acting according to steps recommended by predicting the future :)

So can't we predict destiny? We always comment about destiny once that incident is over. Something like - this happened as it was destined to happen. That means we don't know about our destiny in advance and we don't predict destiny. So while predicting, we predict our future - which may or may not become true. We treat destiny as a bunch of things. Bunch of end nodes of the paths taken. When 1 of the node is reached, we label it as our destiny.

But sometimes I do feel like believing in destiny as 1 fixed node. 1 start point and 1 fixed end point – no matter which path you select. I was destined, not to be with my ex-gf. No matter how I behaved, I was going to end up breaking up with her. At one stage, I knew the future - that she is going to leave. I tried harder, but the things didn't work out - as they were destined to be. One of my friends got married - looking at my breakup. As he didn't want to lose his gf. Now, within 9 months of their married life, they got divorced. What is this if it is not destiny?