For Kierkegaard acedia is a kind of "despair from weakness" which, according to Pieper, "consists in man not daring to be himself, even explicitly not wanting to be himself. He refuses to be what he really is; he does not accept his own being."
Now, this usually occurs as a result a failure of one's being to be affirmed by one's parents. In other words, what begins with a perceived rejection (of the child's developing self) ends in a refusal (of one's being). The child internalizes this rejection, essentially foreclosing his true self before the world can re-traumatize him by rejecting it again. It's a pre-emptive auto-destruction.
It's quite simple really (and also common freaking sense). In order to avoid various developmental catastrophes, the child most needs two things: a person to empathically mirror him and a person to idealize. With obvious overlap and exceptions, the former role often fell mostly to the mother, the latter to the father. Failure of either results in various forms of pathological narcissism and other psychological illnesses.
A normal person never loses the need for both types of relationships. And now that I think about it, it is easy to see how, for example, failure to have a proper ego ideal can result in acedia and developmental stasis. In other words, we always need exemplars to look up to and emulate. I can totally see this in my son. It began with me, but it has branched off into other similarly awesome heroic and virtuous self-objects (the technical term for these relations).
If you want to bring this down to a very concrete level, consider the failure of Obama's self-objects (his worthless mother and alcoholic, bigamist, and manslaughtering father), and how he found his ego ideals in disreputable types such as Frank Marshall Davis, Jeremiah Wright, Saul Alinsky, Bill Ayers, and other lowlife demonoids.
You can't ask someone who has never known normality to understand why, say, we have different restrooms for boys and girls. And our culture is cranking out more and more narcissistically damaged and therefore fundamentally confused people, in my opinion (partly) because of widespread single parenthood and abandonment of children to daycare. How could this not have damaging psychological consequences?
As we've mentioned before, acedia has been poorly translated as sloth, which connotes laziness or lack of productivity. But what it really means is "that a person does not engage in working at his own self-realization, that he refuses to make the required contribution to his own truly human existence" (Pieper).
Again, it doesn't refer to exterior but interior work, i.e., "to the carrying out of [one's] personal being, a duty which we know -- without a word being spoken, yet unmistakably -- that we are required to perform" (ibid.). It's your cosmic duty! What did that fellow say? "The only real sadness, the only real failure, the only great tragedy in life, is not to become a saint."
Failure to answer your telosphone is a Big Mistake, because it's God calling: there's a reason why acedia is a capital sin, because so many other sins flow out of it: "In sloth..., man resists the demand which comes with the dignity of his own status.... above all, he does not want to be that to which God has raised him -- a level of being far above what his purely human nature can achieve" (Pieper).
And the most catastrophic outcome occurs when the narcissistically wounded person props up his own damaged self as his ego ideal. This is why sin and madness flow from the Obama administration like a toxic stream from its swollen headwaters.