Szostak left her native France to study business and play varsity golf at the College of William & Mary. At 29 years old, after a few years at Chanel in NYC she took a leap and gave the acting world a try. Soon after she landed a role opposite Meryl Streep in The Devil Wears Prada. Her most notable projects include the ABC hit series A Million Little Things, Iron Man 3, and Dinner for Schmucks. 

As her career gained momentum, she battled with Impostor Syndrome which pushed her to address her mindset and develop her own 'Playbook’ as a daily practice of Mental Fitness. In her book, Self!sh: Step Into a Journey of Self-Discovery to Revive Confidence, Joy, and Meaning, she guides readers in creating their own Personal Playbook for life—a tool to cultivate a resilient mindset and empower them on their unique journey of self-discovery, learning, and growth. 

As part of her commitment to mental health, she donates half of her proceeds from the book to the mental health organization, Give an Hour.