Dealing with Injuries

Every once in a while, due to the nature of practicing a martial art, you may find that you become injured. Do not despair. The first thing to do is go to a doctor immediately and begin receiving treatment from a professional. If you do not start treating the injury and decide to "tough it out" you may have a permanent loss of ability which will mean that you might never be able to return to full practice.
After treatment has begun with a licensed professional, get an estimate on how long your recovery might last. Give that estimate to your instructor and let him or her know that you plan on coming back at that time. Stay in regular contact with your instructor or fellow students so that they don't just decide you gave up on them.
Another important thing to get from the doctor is a list of approved physical activities. If your arm is broken, for example, you might still be able to practice kicks, or stance work. Get constant updates from your doctor about these kind of approved activities and inform your instructor. If your teacher is willing, go to your karate school or martial arts school to do those exercises.
Remain positive. In my experience, most injuries last more than a minute. That can get depressing because you feel like you are losing all that hard work you did. Don't believe it for a minute. Nothing is ever truly lost, merely misplaced. You will find that even if you have "forgotten" the kata or the moves you were working on just prior to your injury, you will have an easier time remembering them the second time around and it will stick with you longer.
Next, buy a notebook and write down things that you remember about your martial art. It is important that you retain as much as possible and a notebook will help you put into words (which can be easier to remember than some motions) what you have learned. Be as specific as possible and start as soon as possible. When I write these kinds of things down I draw a lot of pictures to give a clearer understanding about what I am working on, for example: when I am writing about a punch, I will draw the fist in various stages, I will draw the fist from various angles and write a description of how the force of a proper punch is evenly distributed through the forearm and the consequences for having a bent or cocked wrist. Writing down what you learn will also make it easier to pass that knowledge on. You will be able to cherish things that your sensei says to you if you write them down more than if you just try to remember the gist of what they say.
Lastly, take your time recovering from an injury. Of course, you want to come back and get to your karate practice as soon as possible. Don't come back too soon, however, because you can potentially injure yourself further. An injury can in this way help you exercise your patience, which is important for any martial artist.