Apologies for the length

Je n’ai fait celle-ci plus longue que parce que je n’ai pas eu le loisir de la faire plus courte.
 
Lettres Provinciales (Letter XVI)
Blaise Pascal (1623-1662)

or translated:

I would have written a shorter letter, but I did not have the time.
 
(literally: I made this [letter] very long, because I did not have the leisure to make it shorter.)

(Such statements have also been attributed to Cicero, Mark Twain and T.S. Eliot, amongst others.)

Unfortunately, this is how I tend to feel about most things I write, or pretty much every talk I give.