This is where you don't want to think too much, especially if you do what you believe. In my case, that means no hereafter. Which means no matter what I do here, I will never know after. Which means that all I am doing here is what I may want to. But to what end?
Carry that far enough, and you can easily get to the point that you realize there is none. A point, I mean, to life. We are amazing organisms (who like to mistreat all the other organisms sharing this place with us - enough in itself to make some want to go away), but that is what we are. More developed than most, that's true.
But in the end we are born, we live, we die. If feeling good, successful, whatever while we are here is enough, fine. Otherwise why bother once we understand?