Interesting thread - What i find most intriguing is the idea that although there are many ways in which something could happen, ie lots of choices and options, but only the one you choose would ever have happened. Like a lot of people say, if i could go back and do something again then they would do it differently, but of course this never could have happened because you cannot change the past. If by some strange event someone did 'replay' an element of their life, i don't think it's possible that they would do anything other than what they had already done, as it has already happened (they had to go back in time), and in order for it not to happen (leaving that choice free so to speak) the idea to do something else entirely would have to be preconceived before the event is even known.
Badly explained, but anyway i find it is easier just to live and try not to regret anything that has happened in the past because it could not have happened in any other way. It's kind of like fate or destiny in that while logically there are many outcomes, there was in fact only one possible outcome because only one of the events could ever, and did, happen. While it is often fun to speculate about what might have happened if circumstances had been different it is satisfying knowing that there was only one possible outcome. Not to mention it lets you get on with your life if you feel it is all laid out before you - Of course as long as this doesn't affect your 'drive' (although if it does, you could say it might have been intended along?), so you can continue through life aiming for the best possible outcomes, but i think adaptability is also one of the most valuable things - there are pretty much always unforeseen occurrences and the best plans are those that can adapt to those unforeseen occurrences.
Although it is indeterminable as to whether life is predetermined or not, (I don't know, but i think it isn't), it is certainly less stressful and easier to live your life as though events could not be any different from what they are, not directly predetermined i guess.