The neighbor who brings your trash cans in when you forget is doing a quiet kind of looking out.

Looking out for somebody is mostly made of things nobody mentions afterward. Bringing bins in costs ninety seconds and requires noticing that you forgot, which means somebody was paying attention to your house while thinking about their own evening. They will not bring it up. That combination of noticing and silence is what being a good neighbor actually consists of.

Do one of those for somebody on your street this week without announcing it. Watch for the small thing that needs doing rather than waiting to be asked for help.