As some of you may know, I was not an athletic kid. I was the last one picked for every sport in school, and dancing was pretty much the only thing I was good at. Every year, we had to do this thing called the Presidential Fitness Test. It involved several activities, including situps, a bent-arm hang (for girls)/pullup (for boys) test, and a mile run. (Looking back, I find it lacking; I think I would add a few things to it. But since I am not the President at the moment, I won't get into that right now.)
Every year, I would fail that test pretty miserably. It was the run and the bent-arm hang that really got me. My endurance and upper body strength were severely lacking, and I always ended up with something like a Certificate of Having Participated, or a Certificate Because We Feel Sorry For You, or whatever it was called.
8th grade was the last year we had to do the exam, and I decided that I'd had enough of being humiliated, and that that was the year I was going to win a Presidential Fitness Award. I didn't train for it (at the time, I didn't really think about those things). But I knew what my weakest events were, and I was absolutely hell-bent on powering through them that year. So when it came time for the run, where I had always plodded along in the back, chatting with my friends, this year, I put my mind to it and ran as fast as my legs would go, even though my lungs were burning and my thighs were killing me. When the bent arm hang event arrived, I held on for dear life, willing myself to hang there although my arms were shaking and my biceps were begging me to quit. And that year, much to the shock of my classmates, I got my Presidential Fitness Award. It was pretty epic.
My point here is that there is a pretty big mental component to training. My colleague, Logan Christopher, is an expert on this. I am convinced that my deadlift numbers would be much closer to my triple bodyweight goal if I could just rein in my brain and focus really hard. There is some interesting research backing up the power of the brain in relation to the strength of the muscles, such as this study and this one. Several studies show that physical performance increases significantly with mental tricks such as "psyching up." Initial studies show that using imagery can even help prevent loss of muscle during a period of immobility.
If you are getting stuck in your training and need something to boost your strength, try imagery. Whenever you are able, imagine yourself performing the feat you desire. Feel the object you want to lift in your hands. Mentally walk yourself through all the steps required to perform the feat, from the stance you'll take to the way you'll begin the lift, all the way to the end of the lift. Do this daily, and often. Contact Logan for more ideas, since he's a font of information about this sort of thing. Let me know how it goes!