This viral post sums up the friend every mom needs

PHOTO: Jessica Johnston penned a viral post about female friendship. PlayJessica Johnston
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Finding adult friends can be hard. So hard, in fact, that when you find one, you celebrate.

In a post that's been shared more than 50,000 times, writer of the Wonderoak Blog Jessica Johnston wrote about friendship on her Facebook page.

"Find yourself a friend who will go to Costco with you on a Tuesday morning because errands and food samples are better together.

"Find yourself a friend who can hold a conversation between crying, spilled drinks, sticky hands, and potty training accidents."

"I wrote this post because I haven’t always had friends like I have now, and I’m so incredibly grateful for them," Johnson told "Good Morning America."

She said true friendship is not about girls nights but more mundane, day-to-day things: "Women need friends in their lives that love them unconditionally and who they love unconditionally back."

The post is being shared so widely, she said, because "women who have this know how precious it is, and women who don’t have [it] are looking for it. I’d say to all the women who’ve commented saying they can’t find anyone like this to take heart in how much it’s being shared. You aren’t the only one who’s looking for this kind of friendship. Now we just have to find each other."

The Southern California mom of four said it's important to "look for a friend to invest into. You won’t know if they’re 'that friend' until you invite them to Costco."