When it happened to me last year, after 30 years, my running suffered at first as I got depressed. Running then became a significant factor in moving out of depression and being able to run in daylight, even twice a day, really helped. I then picked up an injury (racing, not overtraining), which was a pain! In the past few months my running has been back to my standard of ten years ago. I'm working again now - part of me misses the training opportunities!
Edited: 01/02/2013 at 07:50