"Jesus said to her, 'Every one who drinks of this water will thirst again, but whoever drinks of the water that I shall give him will never thirst; the water that I shall give him will become in him a spring of water welling up to eternal life.'"
This comes from a conversations Jesus has with a Samaritan woman who is drawing water from a well. The Navarre commentators remark:
"Our Lord's reply is surprising and really captures the woman's attention. Here is someone greater than Jacob, someone offering her water that will quench her thirst once and for all. Christ is referring to the change worked in every person by sanctifying grace, a share in God's own life, the presence of the Holy Spirit in the soul, the great gift which those who believe in him will receive.
"We worry about the future, we are full of desires to be happy and at peace; a person who receives our Lord and remains united to him as a branch to the vine (cf. Jn 15:4-5) will not only slake his thirst but become a well of living water (cf. Jn 7:37-39)."
We all yearn for satisfaction and fulfillment, and we don't need Jesus to tell us that the things of this world can provide us fulfillment that is only transitory, at best. If we're honest with ourselves, we know this from experience. This transience of satisfaction can be maddeningly frustrating and discouraging, but Jesus offers us hope with His extravagant promise of lasting fulfillment -- indeed, of eternal fulfillment. Is His offer too good to be true? There's only one way to find out, and that's to take Him up on it and get to know Him.