A simple gesture is having a huge charitable impact, causing more people to sign up to give blood in Stockholm, Sweden. And everyone is wondering why no one thought of it before.

Every time a donor's blood has saved a life, they get a thank you text.

Blodcentralen, the Swedish blood service in Stockholm, started sending the messages to remind donors how important their contributions are.

Every time a donor's blood has saved a life, they get a thank you text.

Blodcentralen, the Swedish blood service in Stockholm, started sending the messages to remind donors how important their contributions are.

Donors get their first "thank you" when they give blood, and later, they receive a follow-up text telling them when their blood has been used.

Blodcentralen also updates donors when blood supplies are running low so they can donate more.

"It's a great feeling to know you made such a big difference and maybe even saved someone else's life," Karolina Blom Wiberg, a spokesperson for Blodcentralen, told The Independent.

Also Cool: Teen Athlete Says Apple Watch Saved His Life in the Nick of Time

The initiative came as a solution to the problem of declining blood donations throughout the country; Blodcentralen thought the service would be a good way to keep regular donors coming back more often.

It turns out, the texts have drawn in new donors, too.

People have been posting on social media their stories about the "thank you" texts they receive, and that's encouraged their friends to think about donating, too.

Spread the Idea… (Click and Share) – Photo by DUP, CC