Hi, Kate here. Welcome to WellCast. If you've been here before, welcome back. If it's your first time, check out our introductory video. Long story short, it's 100 wellness exercises in 100 days. You in? Let's talk about two little words that will make you happier. Happy birthday? I do? Nope. Today, we're going to talk about saying thank you. Did you know expressing gratitude is scientifically proven to make you happier? Here's the deal. Humans operate on what's called a hedonic treadmill. It means we generally stabilize at one level of happiness. Going to a party or going to the beach might perk you up for a minute, but generally, your level of happiness stays constant whether you spend a day at the park or at the doctor. Basically, we take the things that make us happy for granted, so they stop psyching us up. By practicing gratitude and constantly examining what you're thankful for and why, you stop ignoring what makes you happy. Essentially, being actively grateful will make you a happier person. But don't take my word for it. Dr. Robert Emmons, a psych professor at UC Davis and author of "Thanks! The New Science of Gratitude Can Make You Happier," has been doing experiments on gratitude for more than a decade. For example, Dr. Emmons gave 300 people journals and divided these people into three groups. One group had to write daily lists of things that they were grateful for. Another group had to write daily lists of things that annoyed them. And the last group, well, they could write about whatever popped in and out of their minds. Batman, strawberries, whatever. Emmons found that people who wrote about things that they were grateful for had a much higher level of well-being than the other two groups. Not only that, they slept better and exercised more. Group A's simple act of writing down what they were thankful for seemed to kickstart their brains. So it's time to kickstart your brain with today's wellness exercise. Take out your WellCast journal. Crack it open to a clean page and write "Things I am grateful for" at the top. If you're the kind of person that likes to be micromanaged, draw three columns and label them "People," "Places," and "Things." Take five minutes each night this week and add things to those columns. At the end of the week, take a look at the list. It's pretty long, huh? It's time for phase two. Time to express a little gratitude out loud to others. Look, we're not saying you have to be one of those people who thanks trees for oxygen. I mean, you can, but just go down your list. Pick one of the things you wrote down and think about who gave it to you. Actually expressing gratitude will help you get off that hedonic treadmill and make you feel better about all the little things. Draft a letter to this person. It's okay. You can explain to them that a YouTube video is telling you to do this, but then get serious. Tell the person what you're so grateful for and why, and then thank them sincerely for it. If you're feeling adventurous, ask them out to dinner and then you can thank them in person. After you send the letter or return from dinner, take out that WellCast journal one last time. Open it up to a clean page and write down how you feel now in detail. Are you like one of the folks in Dr. Emmons' study and feeling pretty awesome? Let us know how your gratitude experiment went. Now that we're all in a good mood, let's do a recap. We learned today that humans take for granted the things that make them happy, and the best way to shake up that paradigm is to spend time thinking about the things that you're grateful for. Studies show that by saying thank you, your general sense of well-being increases. To get that happy ball rolling, write down a list of things that you're grateful for in your journal, pick one, and write a letter to the person who's responsible for that thing.