Satisfy us in the morning with your steadfast love,In this Psalm, there is this building sense that we don't have that many days... not really. When you begin comparing us to the generations of people that have lived, or to the length of time the earth has been here, or more importantly, when you compare us to the creator of us. We don't have all that many days here.
that we may rejoice and be glad all our days.
This is why it is important for us to cry out to our God. Our time is short, but we want to rejoice and be glad all of our days, however few days we have.
God is the eternal one who pays attention to His creation. His lovingkindness (or as it is translated here, His steadfast love) is satisfying to the ones who seek it.