The actress announced on Twitter that she'll be taking part in the 26-mile run in November to raise money for the J/P Haitian Relief Organization.
The non-profit organization was founded by actor Sean Penn in response to the earthquake in Haiti on Jan. 12, 2010. The group provides counseling, educational seminars and medical services.
People immediately expressed their reaction to the news on Twitter.
One person tweeted it will be like a four-hour version of the opening sequence to "Baywatch."