One of my favorite quotes conveying a principle to live by is from The Power of Fun by Catherine Price: "Our lives are what we pay attention to." She has explained elsewhere that what she means by this is that "when we decide what to pay attention to in the moment, we are making a broader decision about how we want to spend our time alive."
After I responded to this idea, I started seeing variations on the theme all over. In How To Know a Person, David Brooks wrote that "[t]he quality of your life depends quite a bit on the quality of attention you project out onto the world." In The Good Life, Robert Waldinger and Marc Schulz quote the French philosopher Simone Weil as saying, "Attention is the rarest and purest form of generosity."