We've all watched someone carrying a full drink glass, moving ever so slowly and cautiously so as not to spill a drop. Yet with each step he takes, the liquid sloshes back and forth, precariously close to spilling over. Alternatively, we've also seen a server dashing through a busy restaurant with a full tray of hot coffee cups filled to the brim without spilling a drop.

How can one individual perform the task so effortlessly while the other struggles?

Some would say it's a matter of experience. That would make sense if we were talking about an uncommon or arduous task Undoubtedly the individual with more experience would have the advantage. But we're not talking about neurosurgery here. This is something we have all done thousands of times before and continue to do on a daily basis.

An overly analytical person might hypothesize a sort of e=mc2 scenario in which there is a scientific correlation between the speed at which someone moves and the relative stability of the liquid they are carrying. A fascinating principle if it were true, but no.

So what's the answer? Simply put, it's a matter of training—not professional skills training but rather training of the mind.

To improve your performance, stop thinking about it.

The restaurant server is focusing on the task of taking the coffee from Point A to Point B. That's all. Her head is clear.

The individual moving ever so slowly and cautiously has an entirely different mental focus. "I hope my hand doesn't start shaking. What if someone bumps into me? I'll be so embarrassed if I drop this." Rather than just carrying the drink, he is focused on the fear of spilling and the resulting public spectacle he believes will ensue. As a result he can't perform the task well, which makes him feel self-conscious and amplifies his anxiety and reinforces a vicious fear-driven cycle. And all of this was generated over something that hasn't happened yet—and may not happen at all.

The lesson here is that thinking too hard about what you're doing actually makes you do worse. If you have to do something that makes you anxious, focusing on your anxiety only serves to amplify it.

Being mindful is one method for you to prevent your incessant overthinking. Focusing less on what's going on in your mind and more on what's going on around you allows you to quiet your mental chatter and be present in the moment.

Now instead of worrying about all that could go wrong, you can just sit back, relax and enjoy drinking that cup of coffee.