Overview
The golf swing drill today will be on "using the ground" properly but it isn't for everyone. Highly skilled golfers are athletes and they generally can do this drill. However, if it just isn't possible or you find your body doesn't "like" this, then please don't do it.

The easiest way to describe what we want to do is to "retain our spine angle" and "point our chest toward the ground" in the impact zone. Most weekend golfers push their butts inward as they begin their downswing. This makes them stand up and their spine straightens.
It's hard for many people to do this but if you can do it, the result is leverage, power and speed.

Drill
Place your golf bag behind you so it just touches your butt at address. Your butt should continue to touch the bag throughout the swing and only leave it well after impact and almost to your follow through.

As your butt stays back, your right foot will remain flat on the ground much longer than it normally does (if you do lose your spine angle). Honestly, it will be a weird feeling and it is up to each person to decide if this move works for them. We don't want to injure anything playing golf. Some people, no matter their age or athletic ability, can easily do this and some can't.

Place the club at the top of your "back/upswing" with your butt touching the golf bag. Slowly begin your downswing without any effort or speed and test your body. If your butt can remain touching the bag, you simply continue slowly down through impact while turning your shoulders and notice your chest points downward toward the ground through the impact zone. If you chest points OUTWARD, not downward, you have lost your spine angle.

If it is easy to do this then simply and slowly continue to a full follow through and hold your follow-through for a count of three while remaining on balance.