Perhaps spending years on my knees weakened my ability to choose and complete my own goals.
When you choose your own goals, by what criteria should you decide they're worthy? Some criteria meant to satisfy some higher goal, right? If you had a highest goal (and I'm not sure humans are even really capable of it, but assuming we are), how could you have chosen it? By what criteria could you decide that it was a good or bad goal, given that evaluation of the worth of anything at all is only meaningful in respect to some goal or other?
Saying "this is an action I want to take" is equivalent to "I believe that taking this action will move me closer to a goal I hold". But choosing a goal is an action in this sense, so there's eventually a recursion problem with choosing your own goals, unless there's some highest goal you hold which isn't chosen by you.
So, if you have a highest goal, it isn't one you've chosen. If you don't have a highest goal, then except in the case where your highest level goals are all compatible (which seems to collapse to the first case, since you could simply view them all as a single amalgamated goal), your goals are inconsistent. Both the case in which you don't get to choose your own goal and the case in which your goals are mutually incompatible are pretty unpalatable, but I don't see a way of avoiding one of them being true.
But choosing a goal is an action in this sense, so there's eventually a recursion problem with choosing your own goals, unless there's some highest goal you hold which isn't chosen by you.
I can't fault your reasoning. So I'll limit it, instead.
In a broader sense of "choice" it is still possible to choose a highest level goal. To wit, you can try pursuing it, and find that you continue to do so, perhaps even more strongly than initially. Alternatively, you can find that you lose all interest. Over the long term as you try different pursuits...
Fifteen thousand years ago, our ancestors bred dogs to serve man. In merely 150 centuries, we shaped collies to herd our sheep and pekingese to sit in our emperor's sleeves. Wild wolves can't understand us, but we teach their domesticated counterparts tricks for fun. And, most importantly of all, dogs get emotional pleasure out of serving their master. When my family's terrier runs to the kennel, she does so with blissful, self-reinforcing obedience.
When I hear amateur philosophers ponder the meaning of life, I worry humans suffer from the same embarrassing shortcoming.
It's not enough to find a meaningful cause. These monkeys want to look in the stars and see their lives' purpose described in explicit detail. They expect to comb through ancient writings and suddenly discover an edict reading "the meaning of life is to collect as many paperclips as possible" and then happily go about their lives as imperfect, yet fulfilled paperclip maximizers.
I'd expect us to shout "life is without mandated meaning!" with lungs full of joy. There are no rules we have to follow, only the consequences we choose for us and our fellow humans. Huzzah!
But most humans want nothing more than to surrender to a powerful force. See Augustine's conception of freedom, the definition of the word Islam, or Popper's "The Open Society and Its Enemies." When they can't find one overwhelming enough, they furrow their brow and declare with frustration that life has no meaning.
This is part denunciation and part confession. At times, I've felt the same way. I worry man is a domesticated species.
I can think of several possible explanations:
1. Evo Psych
Our instincts were formed in an ancient time when not knowing the social norms and kow-towing to the political leaders resulted in literal and/or genetic extinction. Perhaps altruistic humans who served causes other than our own were more likely to survive Savannah politics.
2. Signaling
Perhaps we want to signal our capability to put our nose to the grindstone and work for your great cause. Hire me!
3. Memetic Hijacking
Growing up, I was often told to publicly proclaim things like "Lord, I am not worthy to receive you." Perhaps spending years on my knees weakened my ability to choose and complete my own goals.
4. Misplaced Life Dissatisfaction
Perhaps it's easier for an unemployed loser to lament the meaninglessness of life than to actually fix his problems.
The first theory seems plausible. Humans choke to avoid looking too good and standing out from the pack. Our history is full of bows, genuflects and salutes for genocidal a-holes and early death for the noble rebels.
The second seems less likely. Most similar signaling makes people appear as happy, productive workers, not miserable, tortured artists.
The third and fourth explanations fit well with my experiences. My existential angst didn't fade until I purged my brain's religious cobwebs and started improving my life. These things happened at about the same time, so I can't tell whether three or four fits better.
I'd welcome anecdotes in the comments, especially from people raised in a secular environment. If you don't grow up expecting the universe to have meaning, are you ever dissappointed to find it is meaningless?
But no matter the cause, "What is the meaning of life?" is a question that should be dissolved on sight. It reduces humanity to blinding subservience and is an enemy to our instrumental rationality.
Building instrumental rationality may not be the reason why we're on this planet, but it it is the reason we're on this website.