The Cave

After finishing the game a second time, i have noticed something about the endings:

 Spoiler

If you get the bad ending (You take what somebody else treasures the most and trade it for what you desire the most): The ladder you climb out of the cave is never ending, you never escape. No lesson was learnt. On your next playthrough, the 3 characters you played the last time will be the 3 corpses you take trinkets off at the start of this next run. they got what they're heart desired but we're trapped in the cave until they died.

If you get the good ending (You give back what you desire the most, you don't need it anymore): As you climb the ladder the passage becomes lighter, and you appear on the surface.

I really like that, the game has good storytelling, and the 2 different endings for each character are really different.

I just beat the game for the first time, and I was super unsatisfied because I thought the bad ending was the only ending. How do I get the good ending?