Albert Bandura, on your reading about, for this week, has done a lot of work on the concept of selfefficacy which is essentially the academic term for believing in oneself.
Each one will lift your mood, as will the mere fact that you've tackled and achieved some concrete goals; by doing so, you boost your feelings of self-efficacy, which can boost happiness.
The researchers found that the use of text-messaging significantly increased “self-efficacy” (the effectiveness of treatment, measured by questionnaire).