A bulk of the average golfer's frustration comes from hitting wild hooks. Swinging in to out leads to extreme consequences because hook shots, or shots that curve from right to left and have extreme draw spin, are very hard to control. Drills can help cure this common golf swing flaw.
Poor fundamentals can cause swinging in to out. The first drill to correct this path is a full check of pre-shot fundamentals. Alignment is crucial to prevent this swing path. Your body and flow lines -- your shoulders, hips, and legs -- should be aligned parallel left of target. This means your clubface should be pointed directly at the target, and the rest of your body should be pointed slightly left and parallel to that target as you think of railroad tracks. If your body is closed, even the slightest bit, it unknowingly promotes an in-to-out swing path.
Back of the Ball
You have fought this problem for a while, so drills might take some time to entrench the proper motion. The first drill is to take a range ball bucket, flip it upside down and place it just outside your feet right beside the golf ball. Give yourself a little room between the ball and the bucket so you can swing properly. Take several slow swings at the ball without hitting the bucket to give yourself the feeling of hitting down right on the back of the ball, not from the inside.
Attach the laser pointer to the butt end of your club with the light pointing directly in line with the end of the shaft. Take the club up to the top and slowly bring it down. The position of the light should be directly beside the golf ball. Almost feel like you are holding the club out and extending your arms down to the ball. Repeat this motion 10 times, then take a half-speed swing at the ball. You are training yourself to move away from the in-to-out path.
In theory, you wouldn't try to hit a baseball with an extreme in-to-out path. You would swing directly at the ball and try to drive the ball back to the pitcher. Take your golf club and make some hard baseball swings. In doing so, feel like you would hit a baseball back at the pitcher or even pull the ball to left field. This will give your body the feeling of synchronizing and releasing the club out at the ball, instead of holding in and flipping at the golf ball from the inside.