Given our discussion about how people can be forced to temporarily halt martial arts training due to injuries, I just wanted to say even martial arts legends have suffered this fate.
Here is a passage from Bruce Lee's biography - "It was actually his zealousness that led to an injury that was to become a chronic source of pain for the rest of his life. On a day in 1970, without warming up, something he always did, Bruce picked up a 125-pound barbell and did a “good morning” exercise. That consists of resting the barbell on one’s shoulders and bending straight over at the waist. After much pain and many tests, it was determined that he had sustained an injury to the fourth sacral nerve. He was ordered to complete bed rest and told that undoubtedly he would never do gung fu again. For the next six months, Bruce stayed in bed. It was an extremely frustrating, depressing and painful time, and a time to redefine goals. It was also during this time that he did a great deal of the writing that has been preserved. After several months, Bruce instituted his own recovery program and began walking, gingerly at first, and gradually built up his strength. He was determined that he would do his beloved gung fu again. As can be seen by his later films, he did recover full use of his body, but he constantly had to take measures like icing, massage and rest to take care of his back."
If you want to read the rest of Bruce Lee's biography, here is the page - http://www.brucelee.com/bruceleecom/file/biography.pdf
This article should reinforce the need to stretch & warm-up before starting your regular martial arts training. Here are the wiki sections on stretching and warm-up exercises:
Stretches - http://www.blackbeltwiki.com/stretching
Warm-Up Exercises - http://www.blackbeltwiki.com/warm-up-exercises
Members - Please use this post in order to discuss the training injuries that you have experienced over the years.
Black Belt Wiki