Penn thinks modelling "f**ked" her up.
The 43-year-old 'Private Lives of Pippa Lee' star hated her experiences of attending casting calls in her late teens and early 20s, and says getting her first acting job in a commercial "saved" her life.
She said: "It was destructive to the self-esteem. It f***ed me up. Big time. I'd hear the most awful things, like, 'Her legs aren't long enough. Her t*ts aren't big enough. Next!' There's no respect for you as a human being. You're a commodity."
While Robin - who has two children with her husband, 'Milk' actor Sean Penn
- hated her younger career, one of her biggest highlights was being a member of this year's prestigious Cannes film festival jury to decide which movies would be given awards.
She added: "It was one of the greatest experiences I've had, watching two or three movies every day, then to be at a round table with your fellow artists. It was so mind-altering, so educational. I didn't go to college, but I understand that's the sort of experience you have there."
Robin and Sean have begun the process of divorcing twice, and recently reconciled, with the actor pledging to take a year-long career break to spend more time with his wife, daughter Dylan, 18, and son Hopper, 16, but the actress insists she won't be doing the same.
She exclaimed: "I need a job. I'm actively looking for work."