Katherine Heigl carries son Joshua in new video

Sept. 24 (UPI) -- Katherine Heigl posted a cute video Sunday of herself carrying her son.

The 39-year-old actress took to Instagram following a "back breaking" outing to the grocery store with 20-month-old son Joshua Jr.

The clip shows Heigl returning home with Joshua on her back in a baby carrier. Heigl is parent to Joshua, 6-year-old daughter Adalaide and 9-year-old daughter Nancy with husband Josh Kelley.

"In what universe did I think carrying a 35 pound baby on my back would be no big thing?! Clearly I need @joshbkelley here to be my voice of reason. I'm going to lay down now. Forever," the star captioned the post.

Heigl told fans she plans to bring a stroller to the store from now on.

"Never again. Next time we're bringing the stroller. 35 pounds on my back is far too much. For me, at least," she said in the video.

Heigl said in an Instagram post Saturday she was spending the weekend with her son in Toronto, Canada.

"Spending my Saturday with this dude as my date. My Sunday too for that matter. If he were an actual date it'd be a questionable one. Since he's just a child... and he's mine it's been pretty spectacular!" the actress wrote.

"We hit up the crystal shop here in Toronto @the_rock_store, had a lovely, yet messy sushi lunch and headed home. Lots of walking, lots of people watching, lots of fun! #thoseheavenlydays are all about embracing the chaotic, messy, giggling, shouting, snuggling times with your toddler," she added.

Heigl is known for playing Izzie Stevens in Seasons 1 through 6 of Grey's Anatomy. She portrays Samantha Wheeler on the USA Network series Suits.