Image copyright Ashley Jost Image caption The note Ashley found in the book

When Ashley Jost returned home from her routine Sunday shopping trip she was unaware her groceries contained an unexpected gift.

The 27-year-old, who lives in Columbia, Missouri, was passing the books section in a Target store, when she remembered she had signed up to a reading challenge with her friends.

"We are aiming to read 10 pages of a book a day," Ashley told the BBC. "I saw this book in the aisle, which I had heard a lot about on social media, so I bought it."

The book in question was Girl, Stop Apologizing: A Shame-Free Plan for Embracing and Achieving Your Goals by Rachel Hollis. Later that day Ashley settled down to read it and got a surprise.

"My dog started barking so I got up from reading and threw the book down on the ottoman [couch] when suddenly a five dollar note fell out. I knew it wasn't mine so I thumbed through the pages and saw a pink post-it stuck to one."

The note read: "To the person who buys this book.

"I am 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."

Image copyright Ashley Jost Image caption Ashley (right) with her grandmother

Ashley was strongly affected by the gesture. "I thought it takes someone really special to divert the energy and attention on a bad day to improving someone else's. I know if I was having tough day I'd just want to sit in my pyjamas eating ice cream!"

She decided to take a photo and shared this act of kindness with her followers on Twitter. Her tweet was liked more than 3,000 times and soon caught the attention of local news.

On Facebook, it was shared by the popular page Love What Matters and received 22,000 likes, with many of the comments in reply to the post wishing good will to the anonymous Lisa.

Has she spent the money yet?

"I decided I would pay it forward," Ashley says. "Instead of a one-time act of kindness, I have decided to do one thoughtful thing each day."

So far she has given a gift card to a friend who has been going through a difficult time, bought a drink for the person behind her in the queue at a coffee shop and placed another gift card, with a note, in the library of the university where she works.

"I made a point of ending my note with the same words Lisa wrote to me," Ashley says. "'Remember that you are loved, you are amazing, you are strong'."

Although Lisa's identity remains unknown, Ashley hopes that she is aware of how many people her thoughtful deed has touched and how far her message is spreading.

"My dad told me this morning he bought the groceries of the person behind him," she adds.

Tell us about a time you have experienced the kindness of a stranger. Email haveyoursay@bbc.co.uk

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