Tradition and story time — not medical advice
The Three Princes and the Water-Sprite
Retold for young children from Jataka Tales (retold by Ellen C. Babbitt, 1912), public domain.
A king had three sons, and once, worried for their safety, he sent all three away to live for a while in the forest with a wise teacher. There, a kindly water-sprite lived in a nearby pool, and the teacher warned the princes: "Never go into that water without asking the sprite's permission first, or she may not let you come back out."
The two younger princes forgot the warning and waded in for a swim — and the water-sprite, true to her nature, would not let them leave until they could answer a question about what makes a good person. Neither of them knew the answer, so there they stayed.
When the eldest prince came looking for his brothers, the water-sprite offered him the same test — and he answered thoughtfully and well. "I will free one of your brothers," the sprite told him. "Which one shall it be?"
Without hesitating, the eldest prince asked for his youngest brother — the very one their father had worried about most. "But I could never enjoy my freedom while leaving my other brother behind either," he added. Touched by his kindness, the water-sprite freed both brothers at once, and built her a home nearby, and the three princes lived together happily from then on.
Talk about it (ours, not from the source): the eldest prince wouldn't accept a happy ending unless it included both his brothers. Is there a time you shared something good instead of keeping it just for yourself?
Source: Jataka Tales, retold by Ellen C. Babbitt (1912, The Century Co.) — "The Princes and the Water-Sprite". Public domain. Read the original.
Why public domain: US: first published 1912, more than 95 years ago, so public domain in the US regardless of the author's death date (Project Gutenberg eBook #62514).