Brief gatherings are critical to social movement collaboration across national, regional, and continental boundaries. These assemblies condense the timescales of political activity, creating conditions where seemingly mundane aspects of political involvement can reshape broader patterns of mobilization. Drawing upon ethnographic data collected at the 2007 World Social Forum and United States Social Forum, I demonstrate that the very ecological shifts that create opportunities to collaborate across geographical and social locations can also threaten participants' physical capacity to take advantage of those opportunities. To capitalize on the favorable, but fleeting opportunities at the USSF and 2007 WSF, participants both put forth intense physical effort and disrupted their typical strategies for maintaining their bodies. As a result, participants sometimes reluctantly chose to forego even those forum events which they were passionate about attending. However, in decoupling activists' from their ideological goals, exhaustion provided a mechanism for mixing activists of different political stripes.