John Krasinski dedicates 40th birthday to fundraising for families fighting cancer

Hollywood stars rallied around Krasinski to raise money for the cause.

John Krasinski rang in his 40th birthday on Sunday in the best way possible.

"The Office" star asked fans to donate to a cause dear to his heart -- nonprofit organization Family Reach, which provides financial assistance to families fighting cancer.

"I know what a lot of you are thinking -- wow, he’s old," he shares in a video posted to his social accounts. "Thank you, I am. What you also might be thinking is, 'Really, that must have slipped my mind, what do I get that guy on his big day?'"

"If you’re one of those people who says, 'please no gifts on my birthday,’ you and I are very different because I like gifts. I demand them," he continues. "I’ll go so far as to make you feel very awkward if you don’t get me one. But lucky for you, I’m old school. I like cash."

He then explains his hopes for his big day. "My friends over at Venmo have created a pillowcase of sorts in an account called JKBday,” he shared, explaining that the funds would benefit Family Reach. "So open up your hearts, open up your cyber wallets and make my birthday dreams come true.”

The actor then went on to send some messages to a few of his famous friends to kick off fundraising efforts.

"Hey @ChrisEvans remember when you robbed me of the role of Captain America?... time to pay up?" he tweeted to Evans, to which the actor replied with a GIF of Krasinski.

"Hey @prattprattpratt, Remember you were such a fan of A quiet place? I will literally digitally sneak you into #PartII if you donate!" he sent to Chris Pratt.

Ellen DeGeneres also got in on the fun. "I already got you a gift card to Macaroni Grill but I guess I can cough up some macaroni for this as well. #JKbday," she tweeted.

Krasinski's co-star Angela Kinsey from "The Office" was impressed by his generosity and the campaign.

Reese Witherspoon also shared a video showing support.

Dwayne Johnson explained why the campaign was so personal to him.

"HAPPY BDAY to my brother @johnkrasinski & the amazing charity he’s supporting today @familyreach who provides help to family’s burdened with bill$ as they fight cancer," he wrote in a tweet. "My mom is a cancer survivor so this one means a lot to me and many of you out there."

The actor also shared a video of what his birthday was "really all about," featuring one of the heroes the campaign benefited.

He shared an update on Monday, explaining that the #JKbday Venmo account is still accepting donations for the nonprofit organization.