Spanish Rabbi, Author of book on Ethics "Duties of the Heart (Chovot HaLevovot)"
The earth we live on is so small that even if someone was honored by everyone on our planet it is still insignificant. Also, a person’s lifetime is so short that even if he received honor and approval his entire life, it is so short in comparison with eternity. This is the ultimate success an approval-seeker can hope for, but the reality is that even if you spend you entire life trying to win the approval of others, only a small number of people will know and approve of you. The approval you do gain lasts a very short time and is soon forgotten as if it never was.
Many people fail to enjoy what they have because they keep desiring what they lack. As soon as they obtain one thing, they automatically seek to acquire something else. All the good things they already have are considered as unimportant in their eyes.