LIFE

Life:

1. [U] the active force in animals and plants that makes them different from all other bodies

2. [U] matter in which this force is present and which can grow, produce new forms etc

3. [C;U] the state or condition of being alive

4. [U] (the typical qualities of) human existence

5. [C;U] the period between birth and death; between birth and the present time, or between the present time and death.

6. [C] the period for which a machine, organization, etc., will work or last

7. [C;U] a stated manner or type of existence

8. [U] existence as a collection of widely different experience

9. [U] activity; movement

10. [U] active cheerfulness; VIGOUR

11. [U] the cause of interest, pleasure, or happiness in living

12. [the+S+of] a person or thing that is the cause of enjoyment or activity in a group.

So, LIFE is supposed to be active, cheerful, vigour, interesting, a pleasure and happy. There aren't any negative description for LIFE in this dictionary.

Then, why aren't people happy all the time??