Jennifer Garner and Ben Affleck's Son Left the Sweetest Note in a Library Book -- See the Pic!

If there’s an award for sweetest 5-year-old on the planet, it should go to Jennifer Garner and Ben Affleck’s son, Samuel!

Garner took to Instagram on Monday to share a photo of an adorable handwritten message that the young boy left in a library book.

The heartwarming note read, “Hello, you are loved. I believe in you,” and had a small black heart drawn onto the bottom. The discovery was made by a librarian, who informed Garner of the sweet gesture.

“When the librarian finds a love note your son tucked into a picture book...♥️♥️♥️♥️. #actsofkindness #spreadlove #belikemlkjr #lovenote,” the proud mom captioned the pic.

When the librarian finds a love note your son tucked into a picture book...♥️♥️♥️♥️ #actsofkindness #spreadlove #belikemlkjr #lovenote

A post shared by Jennifer Garner (@jennifer.garner) on Jan 15, 2018 at 8:38am PST

When she's not busy with her kids -- she's also mom to daughters Violet, 12, and Seraphina, 9 -- Garner has her pets to keep her busy, frequently sharing the fun on Instagram.

In December, the 45-year-old actress shared a video showing her reading to her pet chicken, Regina George. Then on Saturday, she baked with her golden retriever, Birdie.

Pretend Cooking Show, Episode 2: @huckcafe English Muffins by @zoenathanloeb. You can see the full episode, in all its floury glory, on my Facebook. #icrackmyselfup #pretendcookingshow #notaprettybaker ----- Huckleberry English Muffins recipe: 3 cups buttermilk 2 tbsp active dry yeast 3 tbsp unsalted butter (room temp) 3 tbsp honey 6 cups bread flour 1/4 cup sugar 4 1/2 tsp kosher salt 1 cup cornmeal ----- 1. Warm 1 1/2 cups (355ml) of the buttermilk in a small saucepan, but do not boil. Place the remaining 1 1/2 cups (355ml) cold buttermilk in the bowl of a stand mixer with the yeast and whisk by hand to combine. Add the warm buttermilk to the cold buttermilk mixture and whisk to blend. Add the butter, honey, bread flour, sugar, and salt and mix on low speed with the dough hook attachment for about 1 minute, until the dough comes together. Increase the speed to medium-high and work the dough for about 2 minutes until smooth. • 2. Transfer the dough to a greased bowl, cover with plastic wrap, and refrigerate for 1 hour. • 3. Sprinkle 1/2 cup (80g) of the cornmeal on a clean work surface and dump the dough out onto it. Sprinkle another 1/4 cup (40g) of the cornmeal on top of the dough and flatten it into a disk with 1 inch (2.5cm) thickness. • 4. Sprinkle the last 1/4 cup (40g) of the cornmeal onto a sheet pan. With a 3 inch (7.5cm) round cutter, cut the English muffins from the dough. Cut them as closely as possible, minimizing the amount of scraps, as you cannot combine and reroll this dough. • 5. Arrange the English muffins, 1 inch (2.5cm) apart, on the sheet pan. Allow the dough to rise for 1 hour at room temperature. Or refrigerate overnight and allow to rise for 1 hour in the morning. • 6. As the English muffins near readiness, preheat your oven to 350F (180C) degrees. When the oven is hot, heat an ungreased griddle or large cast-iron pan over medium-high heat. Jen tip: 275F (135C) for the temperature of your griddle! • 7. Drop the English muffins onto the griddle and cook for about 1 minute on each side, until golden brown. • 8. Return the English muffins to the sheet pan and immediately bake for 8 to 10 minutes, until they feel light.

A post shared by Jennifer Garner (@jennifer.garner) on Jan 13, 2018 at 4:30pm PST

Watch Garner talk to ET about spending holidays with Affleck and their kids in the video below.

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