June 2, 2009, The New York Times — THERE was a time when holidays meant a break from working. Not so anymore, as seemingly every day of the year is National Something-or-Other Day. And a handful of nonprofits, with help from the White House, are working to rebrand occasions like Martin Luther King’s Birthday and Sept. 11 as national days of volunteering, to say nothing of César Chávez Day (March 31), Make a Difference Day (the fourth Saturday of October), National Volunteer Week (the third week of April) and Be the Change Day (this year, Oct. 3). Add one more to the calendar: Mandela Day, July 18, when people around the world will be urged to perform 67 minutes of community service to honor the 67 years (and counting) that Nelson Mandela has fought for racial and social equality. The holiday is the brainchild of the Nelson Mandela Foundation and 46664, the advocate group that bears Mr. Mandela’s prisoner number.