This is a jukugo word, which usually means on'yomi readings from the kanji. Since 人 and 生 both have two on'yomi readings, here's a mnemonic to help you:
Your life boils down to just two things: jeans and a saber (じんせい). Your whole life, that's all you've ever needed, jeans and a saber. What are you, some kind of American pirate?
Life is wonderful.
My life is over. ＼(＾o＾)／
Life is like a banana, you never know how long it will be.