It isn't a phenomenon relegated to tarot. I'm a self-employed artist, author, jewelry maker, and seamstress, and whether I'm doing those things for money or for personal use, I have days or even months where I'm just not feeling it. I generally only write novels in the fall/winter months because hot weather frustrates my author-brain, for example. Last month I was all about wire-wrapping jewelry; this month is about sewing. We get burned out on things, or tired, or for a million other reasons just don't feel like doing something we normally enjoy. It happens!
At the same time, we can't allow apathy to be an excuse. When I don't feel like doing something for my business, sometimes I just need to sit my butt down and do it anyway, because otherwise I wouldn't make any money. The more I do things, the better I become at them, until it isn't an enormous effort to do them even when I'm not really enthusiastic about the process. In your case, I feel that you're jumping in a little too quickly -- would you sell art before you knew how to paint, or apply for a job as a chef when you weren't an expert cook? Tarot is no different, especially since readers come to us with a certain level of expectation; we're there to ease their fears, or interpret advice, or assist decision-making. Looking at a book or at notes while reading for someone, especially a stranger, lowers the confidence of the sitter. As Gregory said, if I went to a reader who relied on books or notes, I wouldn't be impressed because I could have done that at home for free.
When I was first learning, I was incredibly impatient. I wanted to know it all, NOW. I wanted to have all the meanings in my head so that I could rattle them out upon request like multiplication tables. Many new readers feel that tarot is all about learning the meanings and then you're a master, as if memorization is all you need. Unfortunately, it isn't. Similarly, many new readers assume that intuition is something we all naturally have from the start, something you can turn on and off and influence with crystals or candles, and in my experience intuition is nothing like that -- reading the cards intuitively is hard work, harder than learning meanings, and is much more than just looking at a card and letting the meanings "flow" through you. If I waited for a novel to flow through me from above, I wouldn't have wrote six of the things in the last few years, and logically speaking, Novel #6 is a heck of a lot better than Novel #1. Improvement doesn't happen overnight, and intuition isn't something you can learn from guided CDs. The myth of the Muse is as pernicious in the tarot world as it is in the art world, and implies that if it's hard, you're not doing it right -- when in reality, unless it's challenging, you aren't learning.
In short, practice. Practice, practice, practice. Read for friends and family and stuffed animals and television shows and characters in books, read about the weather and stocks, read even when it's hard. If you want it to be your business, spend time learning before setting yourself up as an expert -- your clients and your future self will thank you. But if you're really not feeling it right now and look at tarot as a chore rather than a hobby, take a break! Hell, I took a two-year break and came back clearer than ever, so there's evidence that sometimes, a break is not only good, but necessary for growth. If you still want to practice reading, try something entirely different to cards, like runes or I Ching or a junk oracle. The more you practice reading anything, the more practice you have at interpreting what lies in front of you, the faster your skills will develop. Anything worth learning is worth the work.