General Nouns:
* Life (the most basic and general term)
* Existence
* Being
* Experience
* Journey
* Passage
* Adventure
* Destiny
* Fate
* Story
Nouns Describing Aspects of Life:
* Birth
* Growth
* Maturity
* Death
* Cycle
* Evolution
* Change
* Challenge
* Opportunity
* Struggle
* Success
* Happiness
* Sadness
* Love
* Loss
* Joy
* Pain
Metaphorical Nouns:
* Flame
* River
* Dance
* Song
* Dream
* Puzzle
* Canvas
Nouns Describing Quality of Life:
* Well-being
* Health
* Prosperity
* Fulfillment
* Meaning
* Purpose
Nouns Describing Stages of Life:
* Childhood
* Adolescence
* Adulthood
* Old Age
* Youth
* Middle Age
* Retirement
These are just a few examples, and the best noun to use will depend on the specific context you are writing in.