Whenever you run an Activity, Magic Model Analyst will create a new session for the Activity simulation. If you run the Activity with its context, it will create another session under the session of the context object in the Sessions pane. If you click it, the object of the Activity will appear in the Variables pane. If there is an Activity diagram whose context is the simulating Activity, animation effect on such diagram (for non-silent simulation) will begin playing. 

Note

When you use a read self action in an Activity, normally it returns an object, which is the context of the Activity. However, if the context object does not exist, it will return an Activity execution, which is the Activity's object. 

Running an Activity

Running an Activity.
Animation o fan Activity Simulation
Animation of fan Activity Simulation.