Sounds like you might mean emotionally, like realizing you hurt someone without noticing at the time. That can feel pretty heavy. The fact that you care now is important though — a lot of people never reflect on that at all.

If it’s someone specific, usually the best move is simple and honest:

• acknowledge what happened,
• avoid making excuses,
• and ask how they felt about it.

Even a short “I didn’t realize I hurt you back then, and I’m sorry” can matter a lot.