Suppose like everything its Habit, using the Dominant side of the Body for most things. Over a period of time it alters the biomechanics, one side doing while the other supports and stabalises the action. They say,or the people I know that 95% of injurys start from that problem, and I agree. Thats why its so important, to get in the habit of good body maintainance. Its all down to the eyes, both not seeing the same, bloody things