Gratitude as a character strength involves feeling and expressing a sincere sense of appreciation in life and, more specifically, taking the time to honestly express that appreciation to other people. It can be for specific gifts or caring gestures. Or it may reflect a more general recognition of what the other person contributes to our life. We can be grateful for a thing someone has done for us or created, such as - someone painting a portrait of us, or for the "gifts" of the universe that surround us in life, such as a beautiful sunrise or the fragrance of a lilac blossom.

The most wonderful thing is that, we can build and expand our gratitude. Numerous studies have shown that gratitude is like a muscle. The more we practice gratitude, the stronger it becomes - and the more we can benefit from it.

Perhaps this is why gratitude is one of the most researched topics in positive psychology. The father of positive psychology Prof. Martin Seligman, from the University of Pennsylvania, tested the impact of various positive interventions on 411 people. When the week's assignment was to write and personally deliver a letter of gratitude to someone who had never been properly thanked for his or her kindness, participants immediately exhibited a huge increase in happiness scores. This impact was greater than that from any other activity they made during the experiment, with benefits lasting for a month.

One of the reasons that gratitude has such a powerful impact on us is that it makes us focus on the things we have instead of thinking about what we lack. It reinforces in us a sense of abundance. In addition, grateful people are happier and more satisfied. Gratitude also makes us kinder to other people: more helpful, patient, and trusting.

So, there's no waiting, let's roll up our sleeves this May and build our gratitude muscle. You can do it following the tasks and activities in the mobile app Happiness Accelerator. Enjoy it and be happy!