There will be a reason why you are injured - over training, under training, wrong kind of training, a fall, an illness. The list can go on and, whilst it can be useful to know why you are injured to help prevent the same thing happening again, it won't change the fact that you need to do something about said injury - you can't risk doing the same thing again if you don't get fixed in the first place!
Injuries suck. We can all agree with that. But how you deal with it will most definitely be reflected in your rehabilitation.
Mind over matter
Going from a state of familiarity - knowing what races you want to do, and probably already having an idea of what training sessions that will entail - to suddenly being required to change your focus can be very unsettling, often upsetting. This is perfectly normal. When you're running well, you probably don't always think about what you're doing (which may well be part of the reason you're injured) so to suddenly switch from a very physically based process to one that requires a much more psychological approach is very challenging. Even more so when your running is not 'just' about running for you.
However, it is important to remember that, despite your injury, there is still a surprising amount of training you can still do. In fact, with a lot of what you can still do being core and strength based, it is probably what you (know you) should have already been incorporating in your training plan. The hardest part about this stage of your rehab is being able to accept that it is more about mental strength than physical ability.
Plan your rehab
Onward and upwards as they say. Once the injury has been diagnosed and a treatment plan implemented you will probably be given the go ahead to pretty much do anything except running - this is the usual advice with a running injury, but make sure you follow the specific advice you have been given.
The number one priority of your rehabilitation period is to ensure that your injury heals fully and correctly - whilst there is so much training you can still do, this point must remain at the forefront of every session. One way to do this is to plan your rehab as you would your races - this is now what you are aiming for, at least short term. By all means include some realistic races at the latter end of your rehab period, but you still need to know how you're going to get there - as you should when training for any other race.
The key sessions to include are core engagement and stability, strength, and other cardiovascular training. If these don't already form part of your training then you should ensure you know how to do the exercises properly - in fact, it isn't a bad idea to get a coach or trainer to check your technique from time to time, even if you are doing them regularly. However, here are some things that you may want to consider:
Core stability - base these exercises around the principles of Pilates. Once you know how to engage the right muscles to move safely, you can apply these techniques in your own sessions.
Strength - generally with running injuries, the main thing to avoid is running itself, so the majority of strength exercises should be OK to do but apply some common sense with them. Be cautious with plyometric exercises, especially explosive and impact ones, such as jumps. Compound exercises involve a number of muscle groups and are a good place to start, but, as with everything, make sure you know how to do them properly.
Cardiovascular - the most common cardio alternatives for runners are swimming and cycling. If you can't swim then this may be a good opportunity to learn if you have more time to dedicate to it. With cycling, most (probably all) cyclists will say that you can't beat getting out on the road. However, if you happen to be injured over the winter or are not a confident cyclist then a turbo may be a good investment. I have one very similar to this and is more than enough to complement my run training and rehab. You can find some great sessions for triathletes online or there is software, such as Trainerroad and Swift that can personalise your sessions based on your own fitness.
Note: This may just seem like an added expense when you are already paying for treatment of the injury itself, but all of the above can (and should) be incorporated into your training going forward when you are back running again.
Stay involved with running
I completely understand this may be the last thing you want to do - there are many a time I have stayed away from races when I am injured because the last thing I want to do is see people running, let alone getting PBs. This is understandable and acceptable.
However, on the occasions I have volunteered at parkrun, or supported my friends and teammates at races, I have come away feeling more motivated to regain my fitness so I can join them again. This approach is not for everyone, but generally, you are not going to find a bunch of people who really know how frustrated you are feeling with being injured than fellow runners. You may even find someone else who is in the same boat with whom you can do some training.
Manage your nutrition
One key thing to remember is that you are probably not doing as much training as you are used to, so you need to make sure you keep your food intake proportionate to the training you are actually doing.
Eating the right foods is also important. If you don't already have a good diet then now is a great opportunity to get into a good routine and experiment with different foods and recipes. Protein is something you need to make sure you are having enough of when it comes to soft tissue injuries, along with calcium for bone fractures and breaks.
Using a tracker, such as MyFitnessPal, helps you to see the overall calories you are consuming as well as giving you a breakdown of the macronutrients. A paid subscription will break this down further if you like all the stats and you can also synchronise it to your activity devices. This is not a bad habit to get into for when you are back running to make sure you are getting what you need when you are in full training.
What do you do to keep yourself motivated when injured?