Not getting through the ball

[AlanN]

Hi guys; it's been many a moon since I posted on the site, as my game has been in reasonable shape for my age (70). Unfortunately, I've, subconsciously, got into the habit of hitting at the ball rather than swinging through it. At present, my downswing is finishing in front of me or, just above my head and I can't seem to correct this.

Would somebody please be kind enough to suggest a drill, or swing thought image, which will help me to accelerate through the ball into a proper finish? Thanks