"Keep Training," that is what I tell myself everyday and what you should be telling yourself as well. It may sound simple, but that saying alone has gotten me through injuries, weight gain, weight loss, performance plateaus, self-doubt, and periods of low motivation.
It does not matter whether you just like to train for training sake or you are an elite level athlete trying to perform on the field. Your mind set has to be positive and you must always tell yourself to "Keep Training." Some of the best performers can become complacent because they feel as though they have reached the pinnacle of their sport/profession. That complacency leads to failure in the long run. If you want to be great at something and continue to improve throughout your career, you must adapt the philosophy of continuing to improve and to Keep Training!!!
I watched the Brady 6 documentary last night on ESPN, and while I have never been a huge Patriots or Michigan fan, I really like Brady's story. Here is a guy that had to push through a lot of adversity through college and his early NFL career, but had the confidence in himself and the wear-with-all to keep training his body and mind so that when his chance came, he could capitalize on it, which he did. He could not control what the coaches did or that Bledsoe was going to get injured, but he could control his preparation and training regimen and that is what he focused on. Moral of the story, don't focus on things that are out of your control, and continue to keep training no matter what.
The fact of the matter is that no one is ever going to be at their best all of the time. Injuries happen, doubt slips in, and a downward spiral may ensue if a negative outlook is adopted. When things like that happen, tell yourself to "Keep Training." If your upper body is hurt, train your legs; if your legs are hurt, train your upper body; if you can't do anything physical, train your mind.
Just keep trying to get better, never get complacent. Do not worry about what others are doing, you are not them. Keep training and working hard on every part of your game. Do not worry about the things you cannot control and train the things that you can!