nostalgic

A nostalgic person often feels happy and sad at the same time when they think about something from their past.

You might hear someone say, "I'm so nostalgic for my childhood summers" or "These old movies are making me feel nostalgic." This means that thinking about those times makes them feel a mix of happiness and longing. They're not just remembering; they're also feeling a bit wistful, like something beautiful is lost forever.