I would say a time I did something nice for a stranger was when I noticed an elderly person was struggling to carry her groceries to her car. I offered to help her and she was gratefully like appreciative. After carrying her bags and loading them into the truck we had a brief but pleasant conversation. It was a small act of kindness but it's something that I usually do all the time. I just enjoy helping people but I can tell that it made her day a little bit easier and it was a rewarding experience for me as well because that's just what I enjoy doing.