I have nothing to add to that, but I'll throw in Rav Yitzchak of Volozhin's recollection of the rebuke of his father, Rav Chaim of Volozhin, since I haven't post it in a while:
והיה רגיל להוכיח אותי על שראה שאינני משתתף בצערא דאחרינא. וכה היה דברו אלי תמיד שזה כל האדם. לא לעצמו נברא רק להועיל לאחריני ככל אשר ימצא בכחו לעשות.He regularly rebuked me, because he saw that I did not participate in the pain of others. And these were his constant words to me: This is the entire person. One is not created for himself, but to benefit others with the full extent of his powers.