Don't run down the driveway with a shovel on the ground in front of you while holding the end of the handle up by your face.
The shovel might get stuck on a bump in the driveway and stop. Meanwhile you won't stop and you will run into the end of the shovel handle.
This will make you cry.
And it will give you a black eye.
But when people ask you what happened, you better make up a cool story. Like you were swinging from a vine and hit a tree.
Because that sounds way better than what actually happened.