Answer: Getting distracted
Explanation: When you need to do something, and you spend your time doing another thing that actually does not benefit you in almost any way (like using the phone, playing videogames, etc) is getting distracted, especially with the cell phone, that is a thing that you always carry with you, and makes sounds and things, is a great source of distraction, because it splits your focus in two things, and while you do not need a lot of focus to use your phone, you really need to focus to practice or study.