Difficulty achieving a firm erection, called erectile dysfunction (ED), can be caused by a combination of physical, psychological, and lifestyle factors, including chronic conditions like heart disease and diabetes, mental health issues like stress and anxiety, and habits like poor diet, lack of exercise, smoking, and excessive alcohol consumption. If this problem occurs frequently, it is important to consult a doctor to determine the underlying cause and discuss treatment options, which can range from medication to lifestyle changes and addressing psychological factors.