"Is anyone else feeling rusty?" she captioned the post.
Garner also added hashtags that poked fun of her newfound social media habits, saying she swore she'd never Boomerang or hashtag. Girl, welcome to the club.
The mom of three has been vocal in the past about why she hadn't joined multiple social media sites — though she does have a Facebook page — telling People in 2014 that "the last thing I want to feel is indebted to my phone or computer."
"And the other [reason] is, what would I Instagram that people would want to see," she told People. "There is nothing I would put out that people would want to see. It’s probably best to stay away. They don’t want to see me and my mom friends after kindergarten drop-off."
With over 45,000 views on her kickboxing video so far and an impressive 211,000 Instagram followers, it's safe to say that fans clearly do have an interest in what Garner does and says. She's found a great platform on which she can share exciting peeks into her professional and personal lives, as well as advocate for the causes she holds dear.
In her second-ever Instagram post, Garner shared a photo of herself holding up a sign that encouraged others to donate to Save the Children's Hurricane Harvey relief fund.
"The devastation in #Texas continues to grow and my friends @savethechildren are hard at work helping keep kids affected by #hurricaneharvey safe," she wrote. "You can help us reach families in need by texting HURRICANE to 20222 to donate $25 to the efforts. Thank you for the support!"