Phil Mickelson is right-handed. Do a simple task, such as writing, with your opposite hand. It’s difficult, isn’t it?
Now imagine being a golfer and using your opposite hand to play the sport? That’s what Phil Mickelson does. He’s right-handed, but plays golf with his left.
Why is that?
Another athlete who started playing the sport at a young age, Mickelson mirrored his dad’s golf swing. His dad was left-handed, therefore he swung with his left hand.