Jennifer Garner has vowed to run "one mile a day" for the next two months to help starving children

Alongside a post on Instagram, she wrote: "Happy birthday to me! As I enter a new year, I feel compelled to do something, to put my feet on the ground for kids

"I have been feeling helpless about the world hunger crisis- millions of children are suffering from acute malnutrition and 16,000 children are at immediate risk of dying from preventable causes. I've been lucky enough to find myself on the giving side of life and I am lucky enough to have 16 years as an ambassador and Trustee for @savethechildren, an organization I love and trust. Save is embedded in these communities, committed to caring for the world's most vulnerable.

"It costs $67 to provide six weeks of ready-to-eat therapeutic food (RUTF) to bring one child from acute malnutrition to the chance at a healthy, thriving life.

"I have and, God willing, will continue to donate to Save the Children. This moment in time feels like a larger call to action is needed. So I am running (not my best or favorite activity, I'm a[tortoise emoji]) one mile a day, no matter what, for the next 67 days.

"Run, walk, bike, wheel, skateboard, crawl for kids. Join me for one mile or for 67-any time between now and June 22nd-tag us at #67Strong4Kids and we'll keep each other going.

"If you'd like to donate $6.70 or $16.70 or $67.00, the link is in my bio".

The Hollywood actress also noted that she "couldn't bear" the thought of her own children going hungry, so wants to do her bit for the thousands who are.

Speaking in the video, she explained: "I had an idea. If one of my kids when they were little was hungry going to bed they could always manipulate me into letting them have a little snack.

"I just couldn't bear the thought of my kids going to bed hungry, so knowing that 16,000 kids on this planet are at risk of dying of preventable causes right now because of hunger, I don't know, it's like keeping me up at night. So I had an idea.

"The thing these kids need to bring them back into health and give them a chance at life is ready-to-use therapeutic food."