Currently, I am in a rehab process of a torn ACL and meniscus. In the start phase of my operation I could profit from mental training I did in the past. It helped me to stay motivated. For me it is important to have a final goal (for me this will be to return to the field). Apart from your big goal which you most likely won’t achieve in a long time you should always have small realistic goals which will give you motivation and the experience of success. In most cases only one part of your body is injured so you can always work with the other parts this helps you to stay in your routine and has an overall effect on your body.