This short quote shows you that your time and attention are valuable. Don't waste them.
Your mind is a mouth
Your abilities are not static. You are always growing and moving forward. But are you moving forward in the direction you want? It is easy to lose focus and waste your time vegging out on reality television, endless memes, or other empty things to pass the time. But this is junk food for the mind, and it sends you in the wrong direction, or worse, nowhere. Knowledge, positivity, emotional intelligence, friendship, and so much more are out there waiting to be discovered. You will grow regardless, the choices of each day building on the last. Every once and a while, check and make sure that you're on the path you want. Find things that make you more like the person you want to be and do those things. Explore. Learn. Create. Share.
Ask yourself, "If what I'm spending my time doing right now were in food form, should I be eating it?"