Truthfully, I barely worry myself over those things I don't have absolute control over, but every now and then there is this uncontrollable inclination to be bothered about them. It doesn't do us any good to be worked up with things we have no control of, because they are only there to stress us out and raise our blood pressure.
We must have the knowledge that life often present us with two main options, which could either be things we have control over or ones we don't have control over. It's always in our best interests to live for the moment by making immediate plans and setting realistic short term goals. Because anytime we become engrossed with the thought of what tomorrow holds, we are setting ourselves up for anxiety, stress, if care is not taken, heart breaks.
Advisably, do the things necessary for now that will better your tomorrow but never overstep the present situation by trying to grasp what lies on the horizon.