To respond to "How are you doing?", the best approach depends on the situation and the relationship with the person asking. In casual or everyday situations, simple and polite responses like "I'm good, thanks!", "Fine, and you?", "Can't complain," or "Doing well, how about you?" are common and effective. Often, it's also courteous to return the question by asking how the other person is doing. If the question is asked by someone familiar or when a conversation is intended, responses can be a bit more personal or detailed, such as "Thanks for asking! I'm doing well," "I'm having a great day," or "Honestly, not too well. How about you?" Humor or light honesty can be used if the mood is dark or the relationship is close. In professional contexts, it's advised to keep replies positive and simple, such as "Very well, thanks for asking. And you?" or "I'm doing fine, thank you." Generally, a polite tone, a smile, and reciprocal engagement by asking back "How are you?" are good practices for responding to "How are you doing?"