Jennifer Garner
Jennifer Garner shared the touching note that her five-year-old son, Samuel, inserted in a library book. Pictured: Garner attends the Screening Of IFC Films' "The Tribes Of Palos Verdes" at the Ray Kurtzman Theater on Nov. 21, 2017 in Los Angeles. Getty Images/Christopher Polk

Jennifer Garner is very proud of her son, Samuel.

On Monday, the "Tribes of Palos Verdes" actress took to Instagram and shared a snap of a touching note that read: "Hello, You are loved. I believe in you." The post was so timely for Martin Luther King Jr. Day. According to the actress, it was written by her 5-year-old son and was handed to her by a librarian.

"When the librarian finds a love note your son tucked into a picture book..." Garner wrote in the caption. The "13 Going 30" actress also added the hashtags "#actsofkindness," "#spreadlove," "#belikemlkr," and "#lovenote."

The post garnered positive reviews from Garner's followers who were inspired by her son's kindness. A number find Samuel's note "amazing" and "sweet." Meanwhile, others praised Ben Affleck's ex for raising a good child.

"Thank you for raising an awesome little human. We need more of this," one user wrote.

"Wow! What a beautiful and thoughtful way to spread love and kindness. And from such a young soul! Thank you for sharing!" another one commented.

"Reflects what an excellent job you have done as a mother and that your children are truly loved. Good job mommy," another follower added.

The "Juno" actress and the "Justice League" actor remain amicable following their split in 2015. In fact, they co-parent their three children, Violet, 12, Seraphina, 9, and Samuel. In addition, they still spend holidays as a family and reunite for their children's activities.

On Saturday, Affleck and Garner were spotted together to watch Sam's basketball game. The exes sat beside each other and cheered on their son.

After the basketball game, Garner went home with kids. Meanwhile, Affleck was spotted putting his helmet, leather gloves and jacket on as he departed on his motorcycle.

Just recently, Garner was romantically linked to her "Love, Simon" co-star Josh Duhamel. A so-called insider claimed that that the pair shared intimate lunches and dinner. However, Gossip Cop debunked the reports and stressed that there is nothing romantic between Garner and Duhamel.

In addition, Garner already said that she is not dating. In fact, she is not seeing someone and is not interested in it.

"I haven't been on a date and I am not interested in dating," Garner told Entertainment Tonight. "People want to set me up and I am just like, 'No thank you!' I would not have chosen this life for myself or for my kids. I would not choose to be single or be in this position. It's something that we are working through."