One of the best gifts you can give children this (or any) season is a happy, positive outlook. If they hear mom and dad complaining all the time, that becomes the norm. If the spirit at home is upbeat, they’ll take that in, too.

My friend Heather is the mom of four school-age children who are notably joyful—and also polite. When I asked her secret, she told me she leads by example. “Be kind, be caring, be thankful, and the rest will fall into place,” she said. She makes sure to present everything in a positive light, so instead of “don’t do that,” her kids hear, “it would be better if….”

Heather has an abundance of gratitude and her kids feel it. Though she may be rushing them between hockey games and dental appointments, she takes time to notice the pleasure of a moment. That big-hearted spirit doesn’t come naturally to everybody. But ifyou make it a priority, gratitude can become a part of both the kids’ lives and yours.

It’s never too early to start. “Gratitude” is a big word for toddlers, so with the smallest ones, you can make “Three Reasons We’re Lucky” into a nightly game. Snuggled together after storytime, you start it off. Try something like: “I’m so lucky that I get to be your mom. So lucky that we have this pretty house. So lucky that we fed those funny ducks today. What makes you feel lucky?”

At first, you’ll hear back a lot of what you’ve just said. But that’s okay. Thinking every night how fortunate they are is a lovely way to send children to sleep.

As kids get a little bigger, start keeping a gratitude journal together. Before bed is still a perfect time, and if parents and children do it together, it’s a cozy moment rather than a chore. You can even do the writing while your child talks. The entries should be short and simple—no essays necessary. “Grateful for the bright pink sunset!” is enough to bring a smile.

Knowing that they’ll be writing (or saying) a reason to be grateful every night will change how your kids look at the day. And it will change how you look at the day, too. Somewhere in the back of your mind, you’ll be scanning for reasons to be grateful. Maybe you’ll have that first cup of coffee in the morning and think—Grateful for coffee! And you’re done for the day. Or it’s 4 pm and you haven’t felt grateful yet, so you’ll pause to notice a pretty flower or take a deep breath and appreciate being outdoors.

Your kids will have the same experience. And on days when there doesn’t seem to be any reason to be grateful at all, you can help the figure out how to change their view. For example, if your child frets before bed that her little brother built the bigger snowman, show her how to flip it around. Grateful that I get to build snowmen with my brother!

Having a gratitude journal also means kids have a record of positive moments to read when the world seems grim. By junior high school, children can be dramatic, and what is happening right now feels like it will happen forever. It helps if they have pages and pages to remind them of all the good that has happened and the gratitude they’ve felt.

Kids aren’t very good at keeping life in perspective, but if gratitude is part of their lives, they’re less likely to get upset or frustrated by the pangs and problems of every day. “Children are capable of seeing goodness if it’s presented as a possibility,” says Heather.

The advantage of playing gratitude games along with your child is that you’ll get a more positive view, too. Being grateful can make some of the long days with kids feel a little brighter. And once kids get into the gratitude mode, they can help you get through difficult times, too.

“Little kids are a gift, draining at times,” says Heather. “But if everyone stays in a positive state, wow, that sure does make the good times even better.”

Janice Kaplan is the author of “The Gratitude Diaries: How A Year Looking On the Bright Side Can Transform Your Life.”