They happen because when you stop running, you lose your means of endorphin production. The following strategies are used successfully by many athletes who are faced with injuries.
1. If the injury allows it, cross-train. Pool running, swimming, cycling or any other vigorous aerobic exercise will help to stabilize your mood and enable you to maintain a high level of emotional and physical fitness.
2. Try to see this down time as an opportunity to catch up on special projects you haven't had time for. View it as a period of rest, recuperation and re-evaluation. Perhaps it's time to rethink your workouts and generally "fine-tune" your training program. Your injury may be your body's way of saying, "Attention: Something isn't right. Take a break and re-evaluate."
3. When you get injured, try shifting your focus from what you don't have to what you still have: perhaps a good job, a terrific family, friends, good overall health and a future filled with adventures running-related and otherwise. Keep things in perspective; you've probably had many setbacks in life, yet you overcame those in good form.
Talk to other runners who have experienced injuries. Seek their support and encouragement. Showing your feelings will release tension and help to level out your moods.
4. Finally, laughter is the best medicine for irritability. Research shows that humor and laughter trigger endorphin release and create overall feelings of wellness. So, if and when you next get injured, go rent some comedy videos.