In yoga, we practice a focusing technique called drishti. Simply put, it's just finding a focal point to softly gaze at while you're doing yoga. The reason for this is because we're visual creatures. We get distracted easily - the person on the mat in front of you has a cute top on, there's a car driving by, whatever. By maintaining a fixed gaze you kind of turn all that extra stuff off (or at least put it on a visual mute) and enable yourself to better focus, and most importantly, go inward. If you were to put two people next to one another during a yoga practice - one who had a drishti and one who did not - it would be very obvious to you which person was which. The person without would be distracted, easily agitated, unstable in balancing postures, easily frustrated and would tire quickly. The person with the drishti would be moving effortlessly, powerfully and with a calm, quiet expression. Of course there are other factors to consider - the drishti isn't the magical thing you do to have perfect focus and clarity while practicing - but it is the one thing you can do to make the most out of what you're working with.
Because yoga isn't just about what's happening on the mat, you can use a drishti anywhere. Give it a try the next time you're going for a run, or at the gym lifting weights. Find one place to gaze in front of you, keep your expression soft, and breathe fully. I notice that when I do cardio with a drishti the run feels effortless. I'm sweating and working hard, but I feel calm and focused. You can even try it at work, while driving, or while cooking- the drishti is like the foundation for a meditative state in whatever you do.