Gratitude is becoming quickly a central concept in the area of Positive Psychology. While there are various ways to express gratitude, what seems most important is that you find a way to express it that works for you. Frequently, a gratitude journal is used. You have a specific notebook that is devoted just to writing what you're grateful for. The gratitudes need to stay fresh and you need to be emotionally invested when you write them if gratitude is to develop and deepen. For this reason, often writing daily is not the best route. Nor is reporting over and over the same items for which you are grateful, even though certainly you are still grateful for them. Expressing gratitude requires an "alive" and vibrant experience. You need to allow yourself to feel the gratitude in your body.
Other ways to express gratitude include writing a letter of gratitude to individuals to whom you either have not expressed gratitude or to whom you feel a need to express more gratitude. Reading the letter to the person, in person, often enhances the experience of gratitude as well as draws you and the person closer to one another.
Sometimes simply telling people that you're grateful for something about them, or for the relationship, or for what they did, can boost your experience of gratitude. It will likely, as well, lead to greater happiness.
Certainly Robert Emmons in his recent book, Thanks, has shown from empirical evidence how expressing gratitude does in reality lead to happy lives. And, who would not like a happy life? So, frequent doses of gratitude expression are a route to that goal. Enough cannot be said about the positive outcomes of expressing gratitude. According to Emmons, Sonja Lyubomirsky (author of The How of Happiness), and too many others to mention, some of the other benefits found have included, better physical and emotional well being, improved social relationships, better work relationships, and more optimism.
At first it can be uncomfortable to express gratitude when you're not used to it. So it is with any new behavior. But, over time it can become as routine as brushing your teeth. And it can be a whole lot more fun.