I'm not thankful for anything.
There are a lot of good things about my life. I am where I am today for many reasons. Some of them were from actions taken by individual other people, and I am grateful to them for the specific things that they did for me.
But gratitude in general for being alive and well?
The choices I made along my life path, that have led me here, were my own. The luck I've had has been both good and bad. There was not some fundamental sentient force that has caused my good fortune, to which I owe anything. And I resent the implication, in the whole concept of thankfulness, that I should believe that there is.