When first started using the computer I had the opportunity to choose which hand I wanted to use to move the mouse. I tried left... it was easy. I tried right.. a little bit difficult, but still manageable.
After a few days of testing I came up with a solution or rather a practical reason. I had decided to operate the mouse with my left and I could type the numerical keys with my right. I deal with numbers most of the time and this way I could get a job done faster than most people. Smart eh? :)