As you get older and start to lose some of your flexibility, it gets harder to pivot behind the ball on the backswing—and much easier to just "lift" the club. When you do this, your upper-body weight tends to shift forward toward the target at the top, leading to the dreaded "Reverse C" position and all kinds of poor shots.
One way to self-check for this killer fault is to make some swings using only your right arm, pausing for a few seconds at the top. If you've shifted your weight correctly—that is, if you've rotated your left shoulder under your chin and gotten your upper body behind the ball—your left arm will hang directly over your right thigh.
If your left arm is hanging over your left thigh, however, you've moved your weight too far forward. Work on this drill until you can consistently get your left arm moving deeper on the backswing, and you'll start to hit the ball a lot better.