Many people struggle to concentrate because they have not understood the meaning or importance of one-pointedness in whatever they are doing. They allow their minds to be flooded with thoughts, and they end up performing actions driven by automatic reflexes rather than mindfulness.
Set aside all thoughts whenever you are engaged in any task. This is the way to truly be in whatever you do. This is the way to be in full concentration, and this is how you practice meditation even in the midst of activity. (D-820112-1-1,2)