Learning a New Sport

My shoulder aches from hitting the golf ball 150 times. I am wondering maybe my technique/posture is still incorrect and dad hasn’t noticed it. I think it was because he was just looking at my swings from the right side. Perhaps I was standing up too straight or leaning back too much when I should have been leaning forward. I hope I don’t injure my shoulder or get broad shoulders from playing golf (I am super scared of both).

It’s my second time back at the driving range since Sunday. The first 90 balls, I couldn’t really get into the flow. I was trying to figure out what was wrong - was my shoulder too tensed? During the last 10 balls, I finally figured out a few points.

First, look and aim at the ball when swinging the club down.
Second, when bringing the club down, make sure that the right arm is straight. Prior contact, “drop” the right arm down so that it is straight and follows the golf club’s motion and momentum.
Third, relax your arms and shoulders so that they drop down more during the prep position.

The second point was the more crucial one. Because when I realised my right arm wasn’t straight and corrected it, my swings immediately became better and the shots were more consistent. The momentum feel was back.

Hope my shoulder ache goes away soon.