Upanishads have a wealth of stories and tales which enrich us with various concepts of "Self-realization", "Brahman" or the "Supreme-Being", "Aatman" or the "Supreme-Self" and many other foundational building blocks of Santana Dharma. These stories are not only engaging but leave us with an ever-lasting resonance of thoughts.
Many of these stories are pretty popular such as the Story of Nachiketa and his dialogues with the Lord of Death or the tale of Gargi or Satyakama. However, each time you hear them will provide you with a different aspect.
So If you are tired after work, If you are down, If you are stressed out, listen to these stories and enrich yourself to the fullest.