Because what's going on in your mind is determining how you experience your life. Are you happy? Or are you sad? Are you enthusiastic and motivated, or are you bored and procrastinating? What do you think about when you consider your successes and failures?
With NLP skills you can control what goes on in your mind. Do you control your mind? Or is it controlling you? With NLP skills you can change how you look at your life, and you can start controlling your mind.