I recently realized that what we perceive of as the world is actually the past due to our brain having to process reality. I then began to wonder whether our brains actually take hours, or perhaps even a lifetime, to process reality - so that we are actually always subject to some kind of deistic, singular, unalterable reality...
But then I remembered that we are reactive to our environment. If an external stimulus comes my way, I respond and propagate the randomness that comes from so many choices being made.
Difficult choices make us in control of our lives, remind us that we are alive, and make goals worth striving for...
I suppose we can't ever prove that our realities are mutual, present, or dynamic, but imagine if our choices didn't matter - that's no way to live life.