"In this context, joy (as opposed to sadness) is not to be understood as the joy of doing a mitzvah because the joy of a mitzvah is a high level and it cannot be expected that every Jew be of lofty spiritual stature. However, we mean simply “not-sadness.” Simply put, an understanding that if a Jew doesn’t go around happy about the mere fact that he is a Jew, then he is an ingrate towards the Heaven. It’s a sign that he never really understood the blessing 'You did not make me a gentile.' This Jew is busy contemplating, 'am I a chossid or am I not?' This thinking is pure haughtiness. A chossid?! You’re a Jew!
"Sadness is the lowest level of hell, heaven forfend. What is sadness? The interpretation of sadness is a feeling of “I'm entitled to this or that” and “I’m lacking this or that,” i.e the false sense of entitlement and lack of gratitude, both in spiritual and in mundane affairs.
"If I change places with Avrohom Avinu (and reach all his lofty spiritual levels), what will G-d gain from this? Nothing! He wants me - He already has one Avrohom...
"Bitterness means broken-heartedness. It is a feeling that I haven’t even started on my journey of life since it's impossible to advance even a hairs-breadth without self-sacrifice. And if I have self-sacrifice, then there can be no sadness (which is the opposite of self-sacrifice). If I haven’t even begun the job I was sent here to do - how can I feel entitled, how can I lack anything?! And despite my being derelict from my duties, I still draw breath, I still have all that I need - that’s a great joy and I don’t feel like I’m owed anything. The bitterness that brings about this realization is actually good.
"However, between bitterness (positive) and sadness (negative) is a mere hair’s-breadth of distance. The truth is, the entire Torah is dependent on a hair’s-breadth of distance, as is proven in the laws of shchita (slaughtering): if the majority of the simonim are cut, the animal is kosher. But if only exactly half are, then it's treif. The distance that determines majority is merely a hair’s-breadth.
"YUNGELEIT! YE LADS!
"Ascend to heavens, descend to depths. (“Yaalu hashomayimo, yordu tehomos”). Once you’re treading the waters of tzubrechenkeit (brokenness), you can end up descending into the depths of sadness. Although young people need to learn the difference between sadness and bitterness through their own work, nevertheless let me share with you the following:
"A sign that the soul-searching is brought about by sadness, Heaven forbid, and not by bitterness, is that it causes us to be lethargic, and we can’t stand our own selves and certainly not anyone else. We’re angry and critical - that’s the sign that our feelings of inadequacy were brought on by sadness.
"But following bitterness, we can’t fall asleep. We realize we can’t just be heartbroken. We have not even begun working! So we grab a Gemoro; we pray; we’re happy to see another Jew. We love others, we're not angry or irritable, and we don’t hold ourselves to any level.
"But beware: the best and most refined type of bitterness touches on sadness, Heaven forfend. Whereas the littlest of joys grows out of holiness."