The tale of the two waves
The essence of Vedanta
There were two waves in the Ocean. They were friends. Let us give the waves names and call one "Bhogi" and the other "Shami" . When they were far from the Shore, Bhogi was having a great time, being able to rise 25 feet into the air, far higher than others who were closer to the shore. Shami, on the other hand, kept a low profile and even when rising high, did not feel elated like Bhogi.
As they were moving closer to the shore, Bhogi's elation soon turned to despair on seeing so many other waves shore-crash and perish. Shami, on the other hand maintained composure and was not in the least perturbed.
Every moment became filled with more and more anxiety for Bhogi on seeing the end coming nearer and nearer. Shami had absolutely nothing to fear because Shami knew that it's true nature is water and even after shore-crashing, it will continue its existence as water and perhaps become a wave again.
The word "Shami" in Sanskrit means one who has an equanimous mind. The word "Bhogi" means one who indulges in sense pleasures. An equanimous person, known by the names Shami or Yogi, knows that their true nature is consciousness, and is always happy. The average person, on the other hand, lives for worldly pleasures and develops anxiety over the inevitable declines in life, identifies with the body and thus suffers.
This is the essence of the Bhagavad Gita and the entire of Vedanta.