"Yippee! Let's do sorrow today!" said no one, ever. It is not a favorite space to be. It hurts. It cuts deeply. It implies that permanent endings may be involved. Being fully present and feeling sorrow is certainly not something our society encourages. We are more of the "Get over it!" mindset.
Yet Ms. Buck tells us that sorrow has gifts for us, transformative gifts. Note that if you have experienced a great sorrow, you have come through it a different person. The death of a loved one, a serious illness or accident, or a significant trauma (a pandemic!) changes us forever. It is fairly impossible not to learn something from these experiences, increasing our wisdom and the confidence of knowing we can move through sorrow to a happier place.
Sorrow fully accepted--feeling it and letting it move out of the body--keeps it from being held in and festering. The pain of sorrow enlightens us to the toughness of the human condition and thereby inspires empathy. Judgmentalism fades as we realize that we don't know what is happening with another, that we are all doing the best we can with what we understand at the time. I can say from personal experience that lessening judgments certainly brings happiness, though it is a necessary daily practice. Sorrow can enlighten us to what we truly value, make us more appreciative of the blessings of life. Sorrow helps us to realize the support we have in life, be it family, friends, or Something Bigger. Sorrow is a direct channel to the soul, and that's a potent opening for happiness, and ultimately, joy.