If we build up because it cannot build up automatically we have to build it up with the help of different activities like meditation, exercise and so on. But many of the people face many problems while building focus because first of all we have to make our mind think about it. For example I have a magnifying lenses and trying to generate a fire on a piece of paper. But it totally depends upon me. If I shake my hand focus point will be changed continuously
You also want to be maximally efficient without good focus because every time you mind vendors away from your work you are wasting time. Finally, you want to be as productive as you can because your work output will not be of the highest quality and it will take you longer to do it. Here is a simple reality. If you can't focus effectively, you can't think effectively. And if you can't think effectively, you definitely can't produce the quality of work necessary to be successful