It's almost here! The oven-roasted turkey. Grandpa's secret sweet potato marshmallow casserole. Oh... and that relative you kinda dread talking to. That one who seems to have an uncanny knack for rubbing you the wrong way, every single time.

Whether it's your uber-political uncle or cousin who always asks far-too-personal questions, there's likely one family member you're not that excited to see. Never fear. With preparation, you can still have a happy Thanksgiving. Happiness guru Gretchen Rubin has a solid list of things you can do to ensure Thursday goes as smoothly as possible.

New York Times bestselling author of The Happiness Project and follow-up book Happier at Home, Rubin digs deep into scientific research and uses herself as a guinea pig to discover what works. She also co-hosts a happiness podcast with her sister and blogs frequently to offer tips and advice on how to become your happiest self.

On her blog, Rubin just published her tips for a happy Thanksgiving with difficult relatives. Here are a few that are backed by happiness research.

1. Make your game-day strategy now

Before you arrive, Rubin encourages you to think about how you want to behave. Try to anticipate what you think might happen, then strategize for how you plan to react. She calls it the Strategy of Safeguards.

A study from Happify found 40% of your happiness is controlled by your thoughts, actions and behaviors. You can't change what that annoying relative says, but you can change how you react to what they say.

For example, based on countless interactions with that annoying uncle, you probably already have a strong idea of what he'll say. So make the decision now. Will you hot-headedly snap back at him? Or do you have a plan to maintain your composure with a rational response?

2. Eat your fruits and veggies

I know, I know, you hear this all the time. And the point of Thanksgiving is all the delicious food! Still, hear this one out.

Ruin reminds us how overeating can make us feel -- not just physically, but emotionally. "Feeling bad about having eaten too much can make you feel irritable and angry, which spills over into your interactions with other people," she says.

And, eating healthfully is scientifically proven to increase your happiness. Researchers found adding more fruits and vegetables to your diet can make you as happy as learning of a positive major life event, such as learning you've just landed a new job. "There is a psychological payoff now from fruit and vegetables--not just a lower health risk decades later," said Redzo Mujcic, one of the leaders of the study.

3. Practice gratitude

It's easy to fall down the negativity hole and let your pessimism fester. Instead, focus on the positive stuff. It's not hogwash. Research says this actually works to foster happiness.

Find one or two things to be grateful about, and you'll focus less on the negative stuff. This leads to longer-lasting happiness. Believe it or not, the tactic actually rewires your brain for happiness. One study found that practicing gratitude can increase your happiness by 25%. Happy people focus on what's good, not what's bad.

It's Thanksgiving after all. What do you have to give thanks about? No matter how challenging your family situation, try to find one thing you're lucky to have this holiday season.

Read Rubin's blog post for her complete list of tips and tricks for a happier, less stressful Thanksgiving.