The origins of Thanksgiving lie in the harvest. God-fearing people gave thanks to God for it as they enjoyed its fruits and settled in for the winter. Having exhausted themselves by "doing" in cooperation with God, thus showing their "green," they were now forced into the mode of just "being," thus showing who they really are. In such a process, action gives way to contemplation. That is a kind of death, but it is also a prelude to new life. The approach of winter is the time of Advent, when we await God's coming as a little child and the cycle of life is heralded anew. For all of that, gratitude was surely in order.
In the days when most people worked the land, it was easier to appreciate the coincidence of Nature's rhythms with those of the Spirit. The former were sacramental: a sign and instrument of the latter. But for most of us today, in America, the message needs to become more spiritually explicit so that it can be more voluntarily heeded.
The "attitude of gratitude" is vital for spiritual health. The hard part is cultivating it in bad times as well as good. Farmers are often forced to do that for the sake of mental as well as spiritual heath. But of course none of us are naturally inclined to do it. I find I can do it only when I trust completely that "blessed are the poor in spirit," that the resurrection will follow the cross if we bear the cross as God himself did for us.
As Advent approaches, let us be mindful of the need to become like little children, as God the Son did at Christmas, trusting our heavenly Father even when our suffering is undeserved and we don't at all see how it's "good" for us. And let us not forget the many blessings that we don't deserve either. This life is not about justice, which will only be done fully in the next. It is about the exchange of gifts. At the end of the day, especially today, it is about giving ourselves completely to each other and to God in response to his having given himself to us.