A father and husband, for example, goes downstairs of the house after his wife and children are in bed to indulge in internet pornography. If you ask him why he's doing it, he may likely engage in denial claiming that it's just adult entertainment normal for men and not going to negatively affect family and work. Furthermore, there may also be companion, grandiose thinking assuring his wife or anyone that it's something he can control by himself.
Remember that denial is a hallmark symptom of addictions. Addicts, especially the unremorseful or resistant ones, will typically hide the truth, refuse to talk about the problem, rationalize around, or minimize his condition. Indeed, once a person becomes addicted, he is bound to "mask" the strong hold the addiction has on his life. Denial is used by the addict to provide himself a false sense of confidence as he tries to convince his self and others that everything is fine. So if you're a loved one or friend of an addict, be careful and discerning!
For an addict to rehabilitate or heal, an essential first step is acknowledgement of the addiction and the damaging effects the addiction has in his life. Compulsory psychotherapy/counseling or treatment program is ineffective if the addicted person refuses to get past his denial and recognize the reality of his problem. The unrepentant addict will typically comply with treatment or counseling to avoid unpleasant losses or consequences, such as losing his family, going to jail etc. But he will resume his addiction after buying some time or even after the program is completed.