So...This saying, is something which has helped myself to continue living my life with a Positive attitude at the forefront! 
I had learned this phrase, back in 2007. I had been diagnosed with a Brain Tumor & had to go through Chemo-Therapy at NYU Langone. ANY WAY...As I was going through Chemo one day, I hear this patient in the bed next to me, he was crying & whining to his parents about it being a BAD DAY! That's when a nurse (who MIND YOU she had a "Straight outta Brooklyn" accent & attitude) She came in & says to him "HEY HEY HEY HEY HEY!!!! WHAD UH YUH DOIN' CRYIN' LIKE THAT?!?!? WHAT'S WRONG WITCHU" The kid had sniffled and said "Because TODAY IS A BAD DAY!!!" That nurse then said "NO NO NO NO NO!!!! Just REMEMBER that EVERY DAY is a GOOD DAY! it's ONLY some that are a BIT better than OTHERS!" I took that phrase & told my father (who was sitting in the chair on the other side of my bed) "WRITE THAT DOWN FOR ME NOW! So I DON'T FORGET IT!" I went home & was taught the rest of the school year from home. The following September I returned to school & told the saying to my High School Psychologist. She requested that I write it on a Post-it note for her & place it on her door. By the end of the year, She called me down to her office. I walked in & she had 2 of these printed up! 1 for her office & 1 for myself to take home with me!  This has made myself want to be able to persue some sort of degree where I can help pediatrics, who are going through something similar to what I had to go through, As a Pediatric or Child Life Therapist. My personal life has changed SO MUCH since I began believing in myself with that phrase. I have been able to meet a young woman who is now my girlfriend & we are BOTH Survivors of different types of TBI (Traumatic Brain Injuries) & we HELP each other!