http://www.brainpickings.org/index.php/2013/11/13/open-university-history-of-the-english-language-animated/

To be the light of someone’s life: to be the most important person in someone’s life– to give someone’s life meaning (ex. My son is the light of my life.)

Lead a double life: to have a second, secret life that is usually not socially acceptable (ex. I just found out she leads a double life: she is a lawyer during the day, but a stripper at night)

The best things in life are free: the best things in life don’t cost money: love, relationships, etc…

Risk life and limb: to do something very dangerous where you might get hurt (ex. He risked life and limb to save her from drowning.)

It’s a dog’s life: one’s life is similar to the easy life of a dog (ex. He sleeps until noon, works for a few hours, spends time with his friends and watches TV.  It’s a dog’s life.)

Life is just a bowl of cherries: everything is going well; life is carefree (ex. I love my job and my new house.  Life is just a bowl of cherries at the moment.)

Larger than life: more interesting and more exciting than an ordinary person or thing (ex. He may not be the best musician, but in the eyes of his fans, he’s larger than life.)

Spring to life: to become suddenly alive or more alive (ex. The party sprang to life after midnight.)

Bring to life: to make something exciting and interesting (ex. The bright colors bring the apartment to life.)

Life in the fast lane: a very active or possible risky way to live (ex. When will he get tired of living life in the fast lane?)