High school feels like it was a long time ago, but then there are times when it feels like it was yesterday.
この場合、次のような言い方ができますよ。
ーHigh school feels like it was a long time ago, but then there are times when it feels like it was yesterday.
「高校は昔のように感じるが、ついこの間のことのようにも感じる時がある」
a long time ago「ずいぶん前」
like it was yesterday で「昨日のことのよう」=「ついこの間のことのよう」
ご参考まで!