I'm going to open my brother's side window and tell some guys they look really sad.
Are you going to do it with a positive attitude or a negative one?
With a positive attitude, of course.
Don't yell at people on the street. That's really rude.
Why? They look sad. I'm just pointing out that they are sad and that they should cheer up.
Your intentions seem to be in the right place, just be careful as some people don't take kindly to strangers giving them advice.