St. Paul writes, "Giving thanks unto the Father, which hath made us meet to be partakers of the inheritance of the saints in light...." It is, however, unfortunate that we too often take for granted the blessings of God--either because we do not fully comprehend at what great a price our Lord has wrought our salvation, or--our stony hearts are impervious to the blessings which God continually showers upon us.
Ingratitude is a grave sin that we too often tend to overlook. We generally focus on "major" sins such as murder or adultery. Meanwhile, we pray to God for all sorts of needs, but seldom do we simply prostrate ourselves before Him, our hearts--humble and contrite--overflowing with praise and thanksgiving.
Luke records in his Gospel that Jesus cleansed ten lepers, but only one returned to thank Him--and he was a Samaritan...a member of a despised and oppressed race, with whom the Jews would have no dealings. As such, he was one of the "poor"--"Blessed are the poor in spirit, for they shall see God. And indeed, this thankful Samaritan perceived the Divinity of Christ, falling before Him and worshipping Him. Likewise do we Orthodox Christians perceive Christ's Divinity in the Body and Blood of the Eucharist (which means "thanksgiving").
Every good thing in this earthly life proceeds from above, from the Father of Lights, Who is the sole source of every blessing. We are but paupers before God, without Whom all of our pretended righteousness is but filthy rags.