Over-thinking and worrying is something that contributes to much of our stress and anxiety. We can obsess over such minor things and make us doubt ourselves, filling our mind with negativity. If one can learn to let those intrusive thoughts go, live in the moment, and find a better outlet for the anxiety that these cause, then you can significantly reduce how much you worry, realizing it's not relevant or important to anticipate such things.
5:14 - Ways to Stop Worrying
Reducing Anxiety - http://www.youtube.com/watch?v=QvF-Spx3aUw