reminisce [reminisced, reminiscing, reminisces](to recall the past in a private moment, often fondly or nostalgically) verb [UK: ˌre.mɪ.ˈnɪs] [US: ˌre.mə.ˈnɪs]
怀旧 /huáijiù/ noun
nostalgia(bittersweet yearning for the things of the past) noun [UK: nɒ.ˈstæl.dʒə] [US: nɒ.ˈstæl.dʒə]