I recently started taking a crazy fitness class at my gym. I like the instructor, but I secretly think he may be trying to kill us! I spend most of the class praying for it to be over, keeping one eye on the clock while trying not to fall off the medicine ball, or out of my plank, or messing up some equally torturous position.

When the time to catch our breath and stretch finally comes, I’m always thrilled. However, I often have a hard time relaxing right away because the instructor makes the same error every class: He says “Lay down on your backs,” and it makes me cringe. (My yoga instructors often make this same mistake.)

I’m not going point out my instructor’s error to him because he’s not a writer. But I know this one can be a head scratcher even for writers, so I thought it was worth explaining in my blog:

You LAY something else down. You LIE yourself down.

In the present tense, here are some examples:

• Correct: I lay the fork next to my plate.
• Correct: We lie down on our backs at the end of class and rest.
• Correct: To end this war we must lay down our arms.
• Correct: If we lie down and stay still, maybe they won’t see us.

In the past tense, things get a little tricky. You LAID something else down. You LAY yourself down.

• Correct: I laid the fork next to my plate.
• Correct: We lay down on our backs at the end of class and rested.
• Correct: To end the war we laid down our arms.
• Correct: We lay down and stayed still, hoping they wouldn’t see us.

In the present perfect and past perfect tenses, you HAVE LAID or HAD LAID something else down. You HAVE LAIN or HAD LAIN yourself down.

• Correct: I have often laid the fork next to my plate.
• Correct: We have lain down and rested on our backs at the end of every class.
• Correct: To end the war we had laid down our arms.
• Correct: We had lain down and remained still, hoping they wouldn’t see us.

I realize this can be confusing! But like all grammar, it’s also important. So lay down your pen and think about it before you put anything in ink.

-Maria

This blog post originally appeared on CreateSpace.com. Reprinted with permission. © 2015 CreateSpace, a DBA of On-Demand Publishing, LLC. All rights reserved.