The Natural Born Killers star was heading home from a Los Angeles screening of her new film Conviction when another vehicle slammed into the side of the car she was a passenger in at an intersection in Burbank.
She was taken to hospital and treated for whiplash before returning home to continue her recovery.
But Lewis admits she had to be persuaded to seek medical help - because she didn't think the smash was that bad.
She tells People.com, ""I was two blocks from my house when the car hit my side, the passenger door. The good news is that I was feeling sleepy and leaning in. So, that saved me from more brutal injuries. I didn't actually smash my head. I just got jerked violently.
""The paramedic said to me, 'Juliette, you don't understand. We don't normally see people walk away from a crash that bad... You need to go to the hospital.' He had to convince me.""
Lewis has bounced back from the accident and returned to the spotlight on Tuesday (12Oct10) to attend another screening in New York, but the actress admits she is still coming to terms with what could have been, had she not been so lucky: ""I can't even go into it, it's so sad. I'm still a bit shaken up.""
And the incident, which is being investigated as a hit-and-run by police, has prompted Lewis to enjoy life's every moment.
She adds, ""Live in the here and now, live in the journey. All of that good stuff.""