When I was bored, I would naturally imagine that there was a person next to me and then talk to him. I was so serious that I would say the contents of the conversation out loud.

This behavior is known in psychology as fantasy dialogue mode, and it's a normal human behavior. When we're bored, lonely, or lack stimulation, we might imagine ourselves having a conversation with a character to fill the void. Fantasy dialogue isn't necessarily unhealthy. It can help alleviate anxiety, enhance creativity and imagination, and even become a form of entertainment in some cases. However, if this behavior starts to affect your daily life, such as social interactions, studies, or work, you need to seek appropriate support and treatment. So if you feel bored or need some excitement, you can fill this gap by chatting with friends, doing sports, watching movies, and so on.