Our world works only on egoism, on filling it. Therefore, the upper world is called the opposite of our world.
In Kabbalah, there is a transition from Lo Lishma (for myself) to Lishma (for others) when I make efforts from my egoistic qualities and, as if, acquire the opposite world.
By applying these efforts, I still get egoistic energy, I still try to reveal the Creator for myself, for my own sake. Then, at some point, He gives me the strength to do it purely altruistically, without any connection with myself. This is my reward.
From KabTV’s “Spiritual States” 7/2/21