heres what i think.
Im not very religious but i think what will happen will happen. your'e choices are not made for you but you will always choose a certain choice. refering to the door example, you were not forced to choose the green door but that was what you were going to pick no matter how hard you thought about it. If destiny is a definite reality then there is no way to change it. im not saying i belive or do not belive in destiny for sure but if it does exisist whatever you do is "known" already and trying to change that is useless and does not change anything.
Now that im thinking about it, what if there is no destiny. that means what you do is not predetermined. this would also lead me to belive that amything uneeded or catastrofically useless and pointless could ocurr at any time. The lack of any form of destiny could also mean the lack of any higher entity
I agree that there could be a balance. i do not think that there is absolutly no destiny but i do not feel that we are forced to do everything we do. i think destiny keeps balance and order. I also belive that sometimes human nature is explained as destiny.
after writing this and thinking about it, i have concluded that there is a balance of destiny and free will
im interested to see what other people will write.