The default tick function for an actor or component can be enabled or disabled during the game with the AActor::SetActorTickEnabled and UActorComponent::SetComponentTickEnabled functions, respectively. In addition, an actor or component can have multiple tick functions. This is accomplished by creating a struct that inherits from FTickFunction and overriding the ExecuteTick and DiagnosticMessage functions. The default actor and component tick function structures are good examples of how to build your own, and can be found in EngineBaseTypes.h under the names FActorTickFunction and FComponentTickFunction.