I think my problem is that I keep trying to reinvent the wheel. For instance, in college, my professors, trying to encourage their pupils' sprouting creativity, would assign essays with a list of topics or, inevitably, the wild card (make up your own.) For some reason, it made perfect since for me to make up my own. There was always the clause attached to this option that our topics had to recieve instructor approval before we wrote on. My professors never shut me down (though I wish they would have). Professor Aton let me go ahead and try that essay in which I compared Huck Finn's narrative voice to Daisy Miller's. It wasn't an easy topic and what he failed to mention was that it was plain stupid. Once again, Professor Cook let me take on my great topic, "The Invention of Childhood" as if I would actually do the months of obvious research this would entail and write a mini Masters' thesis. I ended up dumping the topic altogether and scrambling to write anything on Jane Eyre the night before the paper was due.
Obvious failures aside, maturity (what little I have) has taught me a few skills (which is only fair because I have paid dearly for them.) I have finally learned what 99.9% of all the other students I attended school with already figured out: you can write a darn good essay on teacher-assigned topics. There is nothing wrong with exploring irony in Huck Finn, again. There's always something new to say or at the very least a fresh light in which to cast it. It may even be worth risking cliche in order to save oneself the punishment of reinventing the wheel.
Perhaps the trick is learning to accept one's own limitations. I no longer feel let down by all that I can't do; instead I feel liberated by knowing that I probably shouldn't even go there.