Yes, but we are free to fill it up with value.
How pessimistic.

Of course we have no say-so in our existence, we are dealt certain cards, and have to make the best of it. There is a very wise old saying: “it is the journey that matters, not the destination”. Or in another form: “it does not matter if you win or lose, what matters is how well you play the game”.
Where does this pessimism come from? In the national forests there is a sign: “take nothing but pictures and leave nothing but footprints”. If we leave “good” footprints, then we shall live on (for a while) in the memories of those whose life we touched. Since we are biological beings, and as we age, there is a natural “breakdown” of information transmission (the new cells are never identical to the old ones) it is natural that we age and eventually die. Maybe there is a way to arrest or reverse this process, and we can live a healthy life in a 30 years old body - as long as we want to. Maybe this is just a pipe dream. But one thing is certain. We live longer and healthier than our forefathers did. Another wise observation: “The good old times are TODAY”.
Your view of secular philosophy is based on a huge misunderstanding.
I certainly do not see myself as a “donkey”, who is being offered carrot for obedience, and whips for disobedience. It comes from the lack of belief in someone who wields that whip and offers a carrot for “good, obedient” behavior. So your “analogy” is only applicable to believers, not the atheists. As a matter of fact, there is nothing more horrifying than the prospect of eternal “anything”, be it eternal bliss or eternal torture. If people would really consider some “eternal, unchanging” existence, they would reject it immediately. People don’t really want to live “forever”, they simply do not wish to get old and die of age. Read the story of the “struldbrugs” in Swift’s wonderful Gulliver’s travels, and think about it.
Well, this is called facing reality. The “faith” in some afterlife is the quintessential BLIND faith. There is no evidence for it, it is all wishful thinking (read Hebrews 11:1). And there is a “final” end of our existence. It is called “death”. Not fun, and if there would be a benevolent God, he sure could have arranged a better solution.