How do you maintain concentration

[kolpo]

The warlock summon swarm and hungry darkness spells say that you must maintain concentration to keep them active, but how do you do that? When I now cast them do they only last 1 round so I must clearly do something to maintain concentration.

[xwarren]

You should not do anything

I mean you can't attack, cast spells or use items. The concentration will also be broken when you get paralyzed, frightened, confused of polymorphed. So basically you can only move while concentrated