Very often the addiction stems from underlying issues, such as a difficult childhood, low self-esteem, anxiety, depression and so on. We used the addiction as an escape mechanism to run away from emotional pain, or as an attempt to fill a void that we felt in our lives. And once we got hooked, we couldn't stop. Often these issues are deeply rooted in our psyche and began back in our childhood. From our youth, we used the pleasure to medicate our feelings of inadequacy or the void we felt in our lives that may have stemmed from childhood trauma, abuse, or even from social isolation, like just not "fitting in". An addiction therapist, preferably one who is trained in dealing with lust addiction, can help us explore the underlying causes of our addiction and discover where the root of our behaviors may stem from. This is important for the long term, because even if we learn how to fight the addiction, if we do not deal with the underlying causes the disease will often relapse at a later stage.
Besides for the importance of the therapist being trained in addictions, it is best if the therapist we choose has also dealt with an addiction in the past - and broken free. As they say, "it takes one to know one". The mechanics of all addictions are very similar, so it doesn't really matter which particular addiction the therapist may have dealt with.
Choosing a therapist who is not trained in addictions and does not understand the nature of addiction, will often cause much frustration and waste a lot of time and money before we realize that they are not really helping us. They may try to help us find the underlying causes, but an addiction is a disease, and understanding where it stems from alone is not enough to enable us to break free. Just like understanding a broken leg won’t heal it. All the understanding and "self-knowledge" in the world can't take away an addiction - which is a physical disease accompanied by a mental obsession.