Sloth is more than just laziness. Josef Pieper, a popular Thomist Philosopher, explains this very well in his book
Leisure: The Basis of Culture. I found this passage on a website while trying to find a short description of what he talks about in his book. It reads:
...Out of the woods and back to school in the fall, I quickly forgot that early morning walk. But acedia came up again one day while I was reading Josef Pieper. According to Pieper, acedia is that state when "man finally does not agree with his own existence; that behind all his energetic activity, he is not at one with himself; that, as the Middle Ages expressed it, sadness has seized him in the face of the divine Goodness that lives within him."
That this sin is called "deadly" is not strange. Sloth is a deep-seated death wish. Thomas Aquinas said that "mortal sin is so called because it destroys the spiritual life which is the effect of charity, whereby God dwells in us." Acedia poisons our inner well of joy with apathy. It is more than dropping out—of college, of work, of daytime—and more than laziness. Acedia is saying "no" to the "yes" that God said when He created us and called us good. It is suffocation of God’s living breath in us, and rebellion against God’s interaction with His creation....
http://www.gordon.edu/article.cfm?iArticleID=1283&iReferrerPageID=1676&iPrevCatID=134&bLive=1Hate is not the opposite of love, it is apathy. In this way, Sloth is contrary to charity, in that it closes the soul to that which is good, which is God and His Creation. From this, we can infer that even the hardest working, most industrial man can be slothful if he never "stops to smell the roses." I'd say that the opposite of sloth is love, and in order to love, one must be willing to stand still and be receptive (that is, to listen) to the goodness of reality.
An example from my experience is my physics and chemistry classes (I'm in college). I found that I really enjoy listening to lectures more than I like doing the homework. During the lecture, my mind is completely open and receptive to the realities that the teacher is attempting to teach me, and so my mind sees quickly just how fascinating our world really is; it gives me a sense of wonder, it is mind boggling how molecules and atoms work to form mega super structures like the human body, or entire planets, and they all fit together so well in order to do this. It is like reading poetry. However, I don't get that same thrill or wonder while worrying about homework I have to finish or while trying to solve problems. It is that standing still, that listening, that open receptivity, that one begins to find the goodness in reality (and therefore, destroys apathy). Eventually, I find that i am more willing to do those pesky problems for the sake of what is good and lovable. Josef Pieper explains all this better in his books, but there's the jisst of it I think. It might be worth while meditating on The Love of God in your prayers.
I highly recommend reading that book (and also his book, "Happiness and Contemplation"), for at the very least, if you are going to attempt to overcome this deadly tendency, one should at least have a thorough understanding of it, and I think reading that book, despite the title, may give you some answers.