Thanksgiving is simple, but spiritual. You don't have to have a perfect life, or even a particularly good life. The point is to appreciate what you have. And I guarantee there are things you can be thankful for. It's good to give thanks for those.
Giving thanks is about acknowledging the connection between yourself and the world around you. This is good because it acknowledges that you are not the ultimate source of everything in your life. And it focuses on what's going well, despite your lack of control. It nurtures the view that you are a part of something larger than you. Something good.
It acknowledges the grace that exists, that we don't have to earn everything the hard way. In fact, the best thing, love, is completely unearned. It is an infinitely expanding resource. People don't love you more because you are "good enough," or god-forbid "better than other people." Most often, they love you because you love them too.
What better way to spend a day than by giving thanks, with the people you love, for all the good things in your life? What better way to celebrate that love, abundance, and connection than with a feast? Sharing food is an ancient and sacred ritual, practiced across time and cultures. Nothing brings us together like food.
Lastly, Thanksgiving is a day when I'm really proud of this country. It's the perfect example to illustrate that the United States isn't about a particular group of people, culture, or religious tradition. Thanksgiving a major national holiday, and it is for everybody who wants to be part of it. Anyone can come to America and celebrate Thanksgiving because anyone can appreciate good food. In fact, part of the holiday tradition is that we invite others to come and celebrate with us. It's the best of who we are as a country.