At the end of today's Gospel reading (Lk 5:1-11), Peter falls to his knees and declares himself a sinful man. Peter see in himself something that is true of all of us - none of us deserve Christ. None of us have merited God's grace.
The Catechism agrees, describing grace as "the free and undeserved help that God gives us to respond to his call".  We draw our very breath because God wills it, because He has chosen to give us each life.
Thank God today for the gifts He has given you, however large or small they may be. None of us have earned the things we have, in truth, because everything comes ultimately from God. We can - and should - say with St. Paul that "by the grace of God I am what I am". (1 Cor 15:1-11)