What does your instructor say about your training? Have they outlined what areas need improvement and set goals/standards to reach? I believe that setting objective standards is critical to keeping the student informed of progress. Being informed of progress leads to better motivation. Even if the training drags on for a while, the student can see why. Standards can be as simple as "Be able to answer the majority of my questions about topic XXX tomorrow." If the student doesn't know the material well enough, they can see clearly what they need to improve on and how much. That's better than the instructor giving a nebulous, "Well, things were sort of shaky today, and you need to get better before your checkride." How shaky? How much better is needed? Those questions have to be answered to keep the student motivated.
All of that being said, do whatever it takes to relax and keep flying fun. Go flying and just play with the plane. Practice whatever your favorite manuever is and don't worry about the manuevers that are harder. Go get a $100 hamburger with a friend. Or don't fly at all. Go camping for the weekend and take your mind completely away from aviation for a couple days. Whatever you do, don't focus too hard on training and trying to be perfect.
I can totally relate to the spot you're in, but after it's all said and done and you have the certificate in your wallet you'll look back and think, "Hey, that wasn't so bad." It won't be a big deal after you finally get it.