Try to be happy!
Being happy is not always easy, especially when friends tell you that you just have to try to be happier. It may appear so much easier to be naturally happy when someone makes a good joke for example.

Still, the research found that trying to be happier on purpose can work. The here presented research consisted of two experiments. In the first experiment, 167 participants were put into two groups. The first group had the task of consciously trying to improve their mood while listening to music. The second group was asked to relax and passively observe their reactions to the music. Then, participants were either exposed to happy music or with music that was considered neutral, so neither happy nor sad. It was found that participants who had the task to intentionally be happier reported higher scores of positive mood compared to those who had the task to passively observe their mood when they were exposed to happy music. However, when neutral music was presented, intentionally trying to enhance happiness did not seem to work.
The second study confirmed that trying to be happy may not only enhance mood momentarily but also increase subjective happiness in a larger time frame.
So the next time you are sitting in your car and the traffic lights turn red, you could turn on some nice music and try to be intentionally happy. It might work!
Reference:
Ferguson, Y. L., & Sheldon, K. M. (2013). Trying to be happier really can work: Two experimental studies. The Journal of Positive Psychology, 8(1), 23-33.