A key skill in focusing on something is realizing when you have become distracted and bringing your attention back to the task at hand. The sooner you do this, the better. Usually we tend to get carried away by stimuli and become "lost" for long times at stretch. This not only eats up time, but also consumes mental energy that we could have otherwise used for productive work.

I have been successfully using meditation as a "model problem" to train my ability to become aware when I have become distracted and bring my attention back to the object of focus. A classic analogy of mindfulness meditation is that of an elephant (your mind) tied to a post (your breath or whatever is the object of your focus) through the rope of mindfulness. When the elephant strays, the rope pulls it back to the post.

While there seems to be some scientific evidence that meditation does indeed improve your ability to concentrate on any general task, my own conviction arises from seeing first hand the similarity between countering distracting stimuli during meditation and during general work.