The actress showed no signs of emotional stress while visiting Boston Children's Hospital last week

By Michael Miller
Updated July 01, 2015 07:55 PM

If Jennifer Garner‘s impending divorce was weighing on her during a recent visit to Boston Children’s Hospital, she didn’t let it show.

The actress was all smiles while spending time at the facility to research an upcoming role in the film Miracles from Heaven on June 26 – just four days before she and Ben Affleck announced their split.

“She was very friendly. She was coming to do some research for her next film, to ask him some questions that were a part of it, looking to make sure she had her info right,” a hospital spokesperson told PEOPLE. “She was very pleasant, very nice.”

Garner arrived at the hospital by herself wearing a blue and white striped T-shirt, and spent time with Dr. Samuel Nurko, the director of the hospital’s Center for Motility and Functional Gastrointestinal Disorders.

Jennifer Garner Was All Smiles Four Days Before Her Split From Ben Affleck

The film, based on the bestselling novel of the same title, tells the true story of a mother, Christy Wilson Beam (played by Garner), and her sickly daughter, who is miraculously cured from her chronic disease after a surviving a dangerous accident.

The Dallas Buyers Club star and Affleck announced their split on Tuesday after ten years of marriage.

“They plan on co-parenting and doing absolutely everything in the best interest of the kids,” a source tells PEOPLE.

Both Affleck and Garner plan to continue living in the same L.A. estate they purchased together in 2009, and will file for joint custody of their children, Violet, 9, Seraphina, 6, and Samuel, 3.