I don't complain about life. That is related to the happiness of having lived it, fulfilling the goals set and receiving what I expected, without great ambitions.

That is the part of happiness that depends on me, but the feeling of happiness does not depend only on ourselves. The life and actions of other people (very close to us) can modify our own feeling of happiness.
I believe that full happiness does not exist for anyone. Some manage to build a life with more happiness than others. Living unhappy moments allows us to better value those in which happiness triumphs.

I feel happy when I can dedicate time to spiritual growth. It is not difficult to achieve. A book, a movie, a chat with someone interesting, a meeting with friends and family are enough.