I think the most important thing in life is to feel how precious and potential it is to be "alive", whatever it means - having self-awareness, consciousness, agency (mind-body-environment interaction).

After this comes the question of how you use/direct this agency - the "meaning of life", so that you feel fulfillment, you know who you are, what your "story" is (and this story can be seen clearly only afterwards).

The state of constant happiness is bad. One needs times of sadness in order to understand/see/remember the state of happiness. One needs rainy days to appreciate sunny ones.