The challenge, which involves living on less than $1.50 a day, is meant to bring awareness to the billions of people around the world living below the poverty line.
What Affleck neglected to include in his tweet to rally others to take this noble challenge was that he would be doing the challenge for only one day.
So, what's the big deal? Well, the challenge, as stated on the Live Below the Line Twitter page and website, is £5 (about $7.75) for five days, meaning it's a five-day challenge.
A representative for Affleck said the actor would take the challenge for a single day to bring attention to the Eastern Congo Initiative, an organization Affleck founded in 2010. Affleck has not decided on which day he will take the challenge.
Doing the challenge for even one day is tough, but when you tweet to everyone that you're taking the challenge, and you encourage others to do it, you kind of have to do the entire thing for the full effect. Affleck never specified how many days he would be doing the challenge, but the full five days were implied.
Actor Tom Hiddleston has stepped up to the $1.50 a day and is already documenting his meals on Twitter. He posted a picture of his Monday late lunch/early supper on WhoSay. It consisted of egg, carrot, peas and potato.
Do you think it's a big deal that Affleck is doing the challenge for only one day? Let us know what you think in the comments below.