Concentration is the key skill required to develop any other skill.
It is the bedrock of learning itself. Of writing. Of reading. Of listening. Without concentration, you can't do anything else well. You can't read a book, listen to a conversation, understand a lecture, or stick with a task.
The skill is essential to decision making, evaluating options, solving problems, staying on time, and moving through the world safely. Concentration is also important to relationships, because if you can't pay attention to people, those interactions can only go so far.
Even traits such as motivation, assertiveness, and grit require concentration to develop, refine, and apply.
Attention is the most important ingredient we have to living a good, productive life.
So the quality of your attention matters.