When the ball is coming toward you, you are tempted to back peddal so you would not get hit with the ball. But sometimes, because you moved backwards, you get hit.
Watch this example. In this instance, the attacking team continues to possess the ball. But they are retreating because there are so many defenders inside and around the penalty area. In this case, it can be easily anticipated that there would be another attack. Rather the moving backwards, adjust your body orientation to observe the play.