Dear Ven Yuttadhammo,
Reading from the Sacca-vibhanga Sutta, Right Effort is when a person arouses his will, puts forth effort, generates energy, and exerts his mind to eliminate unwholesome thoughts that have arisen in the mind, and prevent unwholesome thoughts that have not arisen in the mind.
On the other hand, Mindfulness is observing, being aware of, and confronting the thoughts that arise in the mind, without getting caught up in them.
If unwholesome thoughts arise in the mind, does being mindful of them alone qualify as Right Effort? Since we are passively observing the thoughts arise and cease, but do not make any intentional effort to eliminate them?