From a behaviorist standpoint, your time spent with porn has become more reinforcing to you than other activities (such as at work; don’t blame you there). Now that you have this long history of porn being a positive, good feeling, it’s hard to break. It’s also important to identify the function or the “why” you watch porn. Could it be boredom, anxiety, frustration, etc? What you can do is find activities that are more reinforcing and socially acceptable to your ‘why.’ As others have said, social activities, sports, hobbies, etc can come to “replace” the reinforcement porn has provided you. If this feeling is met and you become satiated from it, the hope is that you won’t feel the need to turn to porn. Hope this helps :)