I first took a serious interest in Hasidism not intellectually but as life wisdom when I started participating in Jewish life coaching, which I now practice as a coach, for a group of Jewish men in Jerusalem in December 2017. Though I had met enough Hasidim (followers of Hasidism) before, this was the first time to spend 50 hours with some Hasidim in a special setting where we were expected to disclose our innermost agonies.
Of about a dozen participants in these life-changing coaching sessions about one half were Hasidim and the other half were the so-called misnagdim, or the "opponents" of Hasidism. Until then I used to socialize with the latter.
It didn't take me a long time to notice a stark and startling contrast between these two groups of people though I know that not everyone in any social collective behaves stereotypically. The contrast between our Hasidic and non-Hasidic participants was between joy and depression. Naturally, I socialized mostly with these joyful and smiling Hasidim.
Then I started wondering what is in the teachings and practice of Hasidism, and eventually ended up studying Chabad Hasidism for three years since November 2018. Now I know that if you study Hasidism properly, this will inevitably bring you true joy in life.
That's why it was a great shock to me to find those who don't smile among people who daven regularly at one local Chabad house to which I switched last September after davening at a modern Orthodox shul for 16 years. These people who don't smile (nor greet back) may not have studied Hasidism or may not have internalized its teachings.
The most scary people for me are those who never smile. Unfortunately, I've seen that there are such people even among frum Jews in general and at a Chabad house in particular.
The most dominant emotion that is evoked inside me every time I see someone who doesn't smile is compassion as there were times when I myself didn't smile in my mid-twenties.
I believe that smile and lack thereof reflect how much our inner sun is covered by the clouds of our egoic thoughts. I also believe that smile can be infectious as King Solomon says, "Like water face to face, thus the heart of man to man" (Proverbs 27:19 - this English translation is by Robert Alter). If I smile to strangers, they generally smile back to me.
But unfortunately, there are a minority of people whose soul is covered so thickly with the clouds of their egoic thoughts that no smile of anyone else can dispel these clouds. All I can do with them is just to keep smiling to them if I have to see them regularly, hoping and praying that one day they will also start smiling.