There are lessons to learn from every mitzvah. Having recently bought my arba minim (lulav, esrog, hadasim and aravos), some powerful lessons crossed my mind. We all know how everyone inspects the esrog carefully to look for blemishes. It occurred to me that even a "barely kosher" esrog is almost all yellow, and there are just a few spots. This can be a reminder that a few days ago, on Yom Kippur, all of our sins were forgiven, and we are "clean" and shouldn't mess up by getting dirt on our soul. As the Medrash Rabbah in Emor says that the esrog is compared to the heart of a person. On the other hand, even a small speck in the wrong place can render an esrog invalid. So too, we need to realize in these days between Yom Kippur and Hoshana Rabbah (when the Zohar says our judgments are sealed) we should watch that our heart should not get sullied. We are so meticulous about the spots on the esrog, even when the esrog is kosher, but the smallest speck on our soul is more damaging.
It is not for nothing that the Baal ShemTov says that אתרג is the first letters of "אַל תְּבוֹאֵנִי רֶגֶל גַּאֲוָה"- "Do not bring be to the foot of pride". (Tehilim 36:12) At times, people can become haughty showing off how they have the most beautiful esrog. The lesson we should take is that when we say how clean our esrog is, we should say think how we can get our souls to be this clean, and ask Hashem for help in this. As we get closer to Hoshana Raba, most esrogim develop more spots, perhaps symbolic of our getting further away from Yom Kippur and a reminder to do teshuva before Hoshanah Rabbah.
The Medrash compares the lulav to the spine of a person, perhaps a reminder that we should act like an "Adam" and not a animal. An animal walks bent over, while a person walks upright.
The hadasim are compared to the eyes. We should try to look at everyone with a "good eye" and watch our eyes from looking disparagingly at others. We should also try to avert our eyes from the forbidden.
Aravos are compared to the lips. We should watch how we speak of others and how we use our mouth.
These are a few thoughts I had. The point is that although we do a mitzvah because Hashem tells us to, and we have many explanations as to why, we should always try to look for lessons that can make us better people to serve Hashem. When Chazal say the esrog is compared to the heart, it is more than just a nice analogy.
Chag Sameach, a Gut Yor and a Gut Kvittel to all.