Watching porn is a fact of life, but studies have shown that a compulsive use may lead to an increase in ED and a dissociation with real-life sexuality.
2. Psychological conditions
This one is huge. Any disturbance to mental health, including stress at work, hormone imbalance, seasonal depression, anxiety etc. can greatly impact your ability to perform sexually.
3. Unhealthy diet
Our modern diet is extremely high in refined sugars and processed carbs, which in addition to negatively affecting our overall health, has been shown to inhibit healthy vascular function necessary for getting and maintaining an erection. The chemicals and artificial additives found in processed foods may also affect your testosterone levels.