(CNN)Ashley Jost and her friends had just made a pledge to read more books. A week later, a self-help book caught her eye while shopping at a Target in Columbia, Missouri. The 27-year-old bought the book, "Girl, Stop Apologizing," and began reading it when she got home. There was a surprise waiting for her inside.
A gift from a stranger tucked into a book sets off a chain of random acts of kindness
"I was sitting on the couch and the dog started barking at God-knows-what," Jost told CNN. "I tossed the book down to chase after the dog and five dollars fell out on the floor."
She knew the cash wasn't hers because she doesn't carry any, she said. When the college administrator started thumbing through the pages, she found a neon pink Post-it note stuck inside with a handwritten message.
The note read: "I was having a tough day. I thought maybe I could brighten someone else's with this little surprise. Go buy a coffee, a donut or a face mask. Practice some self-care today. Remember that you are loved. You are amazing. You are strong. Love, Lisa."
Jost was deeply moved.
"Random acts of kindness typically happen to strangers on the internet, not to me."
She felt obligated to share the note. So she took a picture and posted it on her Twitter account. "It sort of caught fire," she said.
A few of her friends shared it -- and the local paper picked it up.
Even the book's author, Rachel Hollis, encouraged her followers to pay it forward in their own ways.
Jost's tweet has been liked more than 3,000 times and shared around the world after the BBC got wind of the story. People are pledging their own random acts of kindness -- including her.
Once a day for a week, Jost hid surprise love notes and "lots of Starbucks gift cards" totaling five dollars a day in coffee shops, restaurants and libraries. She felt her college town needed a pick-me-up.
"The end of the semester really is a challenging time for everyone -- staff, faculty and students."
Her stepdad bought groceries for the person behind him in line at a Walmart.
"He was shocked the person ran out after him and thanked him. It made his whole day," said Jost.
Another woman tweeted that she was inspired to commit her own act of kindness in honor of her 19-year-old daughter, who died in a car accident a few months ago.
"I cried when I read that comment," said Jost.
Jost says she plans to do at least one kind thing every week from now on.
"This has shown me the value of checking in with people around me and making sure that I take these opportunities to tell them, 'Hey I appreciate you. Don't forget that 'you are loved, you're amazing and you are strong,' as Lisa said. I don't think we can ever do that enough."
After seeing other media talk about her Twitter post, the mysterious "Lisa" mailed Jost a card to her job on campus.
"She said it made her cry in a good way," Jost recalled. But Lisa still didn't give away who she was. She left no return address, preferring to remain anonymous.
Lisa wrote that it had been a difficult time in her life, Jost said, and she'd wanted "to create something positive -- she never really expected this to happen the way it has."