Do we “suffer” as runners?

In the world of ultra running, there's a lot of talk about suffering and struggling, but mostly suffering. We all talk about it, we hate it, we love it, we glorify it. The challenge. The rawness of it. We suject ourselves to suffering time and time again. The strugglebus. The sufferfest. But what really is suffering? What does it mean to suffer? Can we legitimately call what we experience out there on the trails, running and racing, suffering??