Most amateur golfers see the incredible tour pro's like Sergio Garcia and Dustin Johnson who can create so much powerful lag in their golf swing and immediately try and emulate it. However, the ability to do this requires many small and simple factors to be working initially, before you can focus on the actual action of creating huge amounts of lag in the swing. 

According to Ryan Metcalfe, a PGA professional at the Manor Golf Club, one of the most important subtle factors behind all this is the left hand grip. Many amateur golfers will hold the club very rigid and firm in the palm of their left hand, this leads to a lack of flexibility in your movements with the left forearm, a key factor in creating large amounts of lag in your swing. Therefore, if golfers are already in the wrong grip position at set up, the likelihood is that they will struggle to create the intended lag on their downswing into the ball. 

Metcalfe believes the right correction for this action is to simply move the grip more into the fingertips of your hand, releasing the tension from your swing and allowing you to be more flexibile in creating lag into the downswing. By trying this slight change in your grip position, your overall swing results for creating powerful lag could start to emulate the guys on tour.