I found a technique to be happier. It's about conditioning yourself to refuse to feel confused, which forces you to make things clear as soon as something is wrong, and thus not to make excuses.
I assure you that it helps a lot to stay calm and keep control over your life (and therefore to be in a better mood).
For that I use the key word "confused..." that I remember in the morning in order to keep the habit of reacting to the feeling of confusion (witnessing that something escapes me and which is therefore influencing my moral). What's interesting is that I've developed a sort of natural guilt about feeling in a negative mood, I can't accept feeling gloomy anymore without making the effort to clarify what's wrong and reach a satisfactory solution!
I therefore strongly advise you to try this discipline which allows you in a certain way to no longer let yourself be conditioned by laziness in the confrontation with the problems that you encounter in your daily life.