A period of time where a player must perform some action before an effect will happen or before an effect is dismissed. Game rules specify what sort of role play flavor a player should do during Activity time. From the Accelerant core rules:
"Activity time is used when you must perform some action such as repairing an item or mending wounds before an effect will take place. In order to satisfy either requirement you must spend the time uninterrupted. If you are forced to break the conditions of Activity time then that attempt ends and you must start again from the beginning."
"Activity time represents something that requires your concentration. Activity time might be required to repair armor, mend wounds, or meditate to remove an effect. You must spend the time role playing in a manner appropriate for the skill or ability you are using. You may talk with others during this role play time if you wish so long as the skill or ability description does not have additional restrictions in its description. Activity time requires that you stay in the same area as you role play the activity. You cannot walk or run. You cannot use other game skills, used called attacks, or use called defenses during this time. In addition, if you are affected by an attack with effect that is not beneficial your activity time is interrupted and you must begin that time again. Skills and abilities which require activity time do not overlap; what this means is that if you have two different skills that require activity time to perform that time spent on one ability cannot be applied to any other activity. You have to role play each activity time separately to use the ability. Effects that prevent you from using game skills also prevent you from spending activity time to refresh abilities. Resting time and Activity time do not overlap."
"Travis and Gerard, for example, each have a skill that provides armor points. Travis has a skill that requires one minute of rest to refresh his armor points. Gerard has a skill that requires one minute of activity to refresh armor. Both sit down to rest off a Weakness effect. During that time, Travis may also refresh his armor points. Gerard will still have to spend one minute of role play to refresh his armor."