There is a monster that stalks the Thanksgiving holiday. It chases away gratitude and replaces it with longing.

The monster’s name is envy.

You will know the monster is lurking if you are seated at the Thanksgiving table and start mentally comparing yourself with others and feeling short changed.

Your car seems too old, your salary too low and your weight too high.

The tendency to see our glass as half full is understandable in a consumer society. After all, envy is the very soul of advertising, which constantly tells us we are not thin enough, rich enough or young enough.

In the world of advertising, the solution seems so simple: Just buy the right products, and you will finally be acceptable.

The signs of the envy monster are everywhere. Yes, I have a job, but what I really want is a promotion like my friend just received. Sure, I have a house, but it could be larger and more elegant, like the one down the block.

And, yes, it is true that my latest medical check-up was good, but shouldn’t I be considering some age-defying surgery so I can resemble the folks in Hollywood?

Unfortunately, the envy monster produces a nagging restlessness and ever-growing discontent that wreaks havoc with gratitude.

Think about it: Even as you are driving your sparkling new car off the dealership lot, you may already be hearing ads about the wondrous improvements in next year’s model.

And even as you are enjoying a respite at the seashore, you may be perusing travel magazines to plan a far more spectacular trip next year.

I am basically a cheap date. I have never been to Europe, and it is likely I will never get there because I am quite happy sitting on the deck, staring at the forest in our backyard.

Still, there are times when the envy monster stalks me and gratitude is tough to conjure up. At these times, my life seems terribly dull and predictable.

Surely there must be some great adventure that awaits me somewhere else. And surely I should be living somewhere more exotic than in our old house in Decatur.

The ocean quickly comes to mind. Yes, that’s it, I decide. A seaside home would make me perfectly happy, wouldn’t it?

And then I run into folks who live on the ocean’s edge, and they’re wondering why happiness still evades them.

It is tempting to fall prey to the big lie of consumerism, which is this: Never be satisfied with what you have. Keep striving to get more, even if that means digging further into debt.

Then comes the Thanksgiving holiday, which encourages us to sit down and thank God for all he has given us. But if we continue longing for what we don’t have, counting our blessings will be tough.

There is an antidote to this dilemma: Try making it a daily habit to list all your blessings. It soon becomes clear that our real gifts don’t come from the mall, nor do they drain our bank accounts.

Whenever I say my evening prayers, I try to remember gratitude: “Thank you for my faith, my health, my job, my ability to write. Thank you for my family members, my dear husband and my friends. Thank you also for the chipmunk I saw earlier today.”

“If the only prayer you say in your life is ‘thank you,’ that would suffice,” wrote Meister Eckhart, a 14th-century theologian.

The word “Eucharist” means thanksgiving, and how appropriate that is! After Holy Communion, the prayer that often rises in my heart is: “Thank you, Jesus, for nourishing me with your love.”

The fall holiday beckons us to thank God for all the things that come without price tags, such as a sliver of sparkling moon in a charcoal sky. A tangle of trees bedecked with multicolored leaves. And the red-tailed hawks swimming through the clouds above them.

Let’s not forget our very lives.

“We exist because we have been willed into existence,” writes Anthony Bloom in “Beginning to Pray.” He adds that our lives are a great sign of God’s love.

And for me, another sign is the appearance of new life on our orchid plant.

This plant has sat in our bedroom for about 10 years, and it usually resembles a nondescript mass of wimpy green stalks.

Every few years, however, the plant does something festive. Prompted by a mysterious impulse, it sends out thin shoots upon which there suddenly appear tiny purple flowers with yellow etchings.

First one little face appears and then another, with the full regalia of blooms continuing for months. Sometimes I wonder: Who painted the stripes on these amazing little faces?

A scientist might explain how the plant evolved this precise pattern over the eons because it would attract just the right bird or create a camouflage or blah-dee-blah-dee-blah.

But I like the simpler explanation: God is an artist and he made these fancy orchids for us to enjoy.

Counting blessings can be relatively easy if we keep in mind Christ’s advice: We must have a change of heart and become like children to enter the kingdom of heaven.

In truth, children are thankful for small things, which cost very little: a delicious cookie and a day at the park. They will rarely pass by the tiniest flowers without stopping to admire them.

Let’s pray this Thanksgiving to banish the envy monster from our hearts. Let’s follow the example of the little ones and be grateful for blessings often overlooked.

Most of all, may we praise God for the greatest gift of all, which he lovingly gives us at every Mass: his body and blood in the Eucharist to nourish us for all eternity.