The Rebbe Returned the Blessings
Have you ever wished someone "Good Shabbos", but instead of returning the greeting he just continues walking, blank faced? After all, you don't actually know each other. Or perhaps you've passed a friend and tossed a "Hi, how are you?" over your shoulder, continuing on your way without waiting for a response.
In the summer of 5742, my grandmother, Mrs. Chaya Majesky a"h, visited the Rebbetzin together with her future daughter-in-law, Rishe Majesky, and Rishe's mother, Mrs. Rechi Paltiel. Towards the end of the brief visit, the Rebbetzin asked my grandmother (in Yiddish), "So, is your hand still the only Jewish one on the subway?"
My grandmother was both touched and taken aback. Several years earlier she had met with the Rebbetzin who had asked her about her work. My grandmother told the Rebbetzin about the knitting factory where she worked, and mentioned that on the train ride home through a predominantly non-Jewish neighborhood, hers was often the only Jewish hand holding the railing.
Now, several years later, the Rebbetzin remembered and made sure to ask for an update.
Would You Steal?
The Rebbe's first public address after the Rebbetzin's passing was one of appreciation and blessing.
Upon the conclusion of the seven days of mourning, the Rebbe addressed his chassidim , quoting the Gemara: "If a person greets you with 'Shalom,' and you do not reciprocate with 'Shalom,' you are considered a thief." 
In halacha, the term thief only applies to a person who takes unwarranted possession of someone else's belongings.  If an employer owes wages, for example, he must pay up, but it is referred to as "withholding," rather than stealing, since the money was never in the employee's possession.
It's clear, the Rebbe explained, that from the moment a friend greets you with the blessing of "Shalom" he becomes entitled to a "Shalom" in return, because you, in effect, have taken possession of his "Shalom." If you do not return the greeting, you are considered a thief.
The Rebbe then related this halacha to himself, telling the chassidim that he wished to respond to the blessings and good wishes they had extended over the week of shiva.
Back to Us
As the Rebbe's and the Rebbetzin's children, we should strive to emulate their behavior, taking the time to truly focus on those around us, greet them properly, listen to what they tell us, and show sincere interest in their lives.
Sometimes, looking up from our smartphones and making eye contact is sufficient. At other times, we may need to invest more. As my father used to say, "Before you ask someone how they're doing, make sure you have the time to listen. They may actually tell you!"
May we merit "Hakitzu v'ranenu..." with the Rebbe and Rebbetzin amongst them.
Rabbi M. Lipskier
 Sefer Hasichos 5758 pg. 271.
 See Rambam hilchos g'zeila v'aveida 1:4.