Just like a day is divided into day and night, so is a person’s life. (You get a sunrise when you are born and a sunset when you pass away.)
You can use this as a simpler way of living your life. For instance take the way a kid grows up; he or she will grow into an adult that reflects the way s/he was brought up. So if you want to have a responsible and smart kid, you need to start when they are young.
If you are looking to be the kind of guy who lives a great and productive, you need to start planning your days better. Early mornings are a great to start; this gives you time to do your job and other side projects, and still have time for your family.