Garth Brooks and Trisha Yearwood pick up the hammer from the Carters

Country music stars Garth Brooks and Trisha Yearwood are building houses this week in Charlotte, North Carolina. They are participating in Habitat for Humanity's 37th Jimmy & Rosalynn Carter Work Project.

This annual work project is named for the former president and his wife, Habitat's most renowned volunteers. From 1984 to 2019 they helped build, renovate and repair 4,390 homes, working alongside more than 100,000 volunteers in 14 countries.

President Carter, who began receiving hospice care earlier in the year, marked his 99th birthday on October 1. The country music power couple was working on the Habitat build in Charlotte and led fellow volunteers in singing happy birthday on social media. Brooks believes the Carters would've been there, volunteering in person if they could. But their presence was still felt.

"Both of them, President Carter and Rosalynn, show signs of strength that I would never find. But what I love about it is the example." Brooks told CNN.

"We are here to honor their legacy and continue the work that they are continuing to do; just because they have retired from this project and are at home does not mean that they are not here, so we feel very lucky and very fortunate to still be a part of what they stand for. "

"And I think what they stand for is truly loving your neighbor," added Yearwood, who hosts a show on the Food Network which is owned by CNN's parent company, Warner Bros. Discovery. "They are just great examples of how to be, and they fit Habitat so well because Habitat is all about helping your neighbor, about lifting each other up."

This year's project in Charlotte is building 27 single-family homes. The future homeowners are working with the volunteers on the construction, and will be paying mortgages for their new homes. Habitat for Humanity does not give away these houses, but make them affordable for families in need.