If you watch close enough, they tend to speak of themselves mostly in the past, present or future. Always saying things like "I went to the bar last night" and "I played basketball when I was in highschool" and it is so different from saying things like "I’m tired" or "I want chocolate." And it’s even different from saying things like "I’m going shopping tomorrow" and "I can’t wait until my birthday."
It’s all about where people see themselves.
If you’re nostalgic and miss things about the past, it’s going to come out in the way you speak.
What’s even more fascinating is listening to people describe themselves. Saying things like "I play piano", compared to "I’m artistic" says a lot about a person’s personality.
It’s funny but sometimes if the world is watching close enough, it often knows you better than you know yourself.