It's hard to put an exact measure on what "too far" is, especially when it comes to acts of kindness. However, to my mind, if someone is more than a few feet away and you can't even discern their facial features, it's probably safe to say they're out of reach. The beauty of kindness is that it's flexible and can be adapted to different situations. A gentle wave, a kind smile, or a small gesture can often do the trick!