She is the daughter of Ivaldi and mother of Skadi with her brother, Volund. She later became the wife of Bragi. Idun is more widely known as the keeper of the Ellilyf Asa 'The Gods' Remedy Against Old Age," which is the same as the Manna Mjotudr only here the fruits are consecrated for a different purpose—to keep the Gods and Goddesses young. In both instances we see the fruits as containing the essence of youth, for in the one instance this quality is bestowed upon our divinities, and in the other it is the force that brings children into the world.
Idun was granted the ability to consecrate and distribute the apples by Volund, who discovered the formula for this and would only give it to his sister/lover. Volund later turned against the Gods for what he felt were injustices committed against his works of craftsmanship, and for a spell Idun and her sister swan-maids, joined Auda and Sif, joined Volund, Egil, and Slagfin in the Wolfdales where they plotted their revenge on Asgard. But the maids were not happy there, for they grieved the loss of their divine status, exchanged their swan-guises for wolf-skins to keep warm, and transformed their demeanors so that they delighted in guile and harm for the worlds. But after eight years of this they began to long for their former lives, and on the ninth they left the Wolfdales to return to Asgard. But Idun's love for Volund was great, and she later made her way back to him, only to then be captured by Loki and brought back to the Gods, whence Volund died chasing after what had been taken from him.
This duality of natures, in dealing with the swans that swim in the waters and fly in the sky versus the wolves that howl at the moon in the ice-cold mountains, has the same theme in the story of Idun's daughter Skadi and her marriage to Njord. The two were married but each longed to be in their own home, which are more in tunes with their natures. Njord even said: "Hateful for me are the mountains, I was not there long, only nine nights. The howling of wolves sounded ugly to me after the song of swans" (LV.12). Skadi, in turn, could not stand living near the sea and said as much, so the two ended up making a compromise because we we find that they are still married later in the lore (LXXVII.1). The lesson here is that even though we cannot deny our true selves, we can always find ways to make it work with the ones we love. If we compromise our realm of possibilities lies wide open.
Idun's spiritual lesson is in the invigoration of the Spirit. We must always be in search of ways to strengthen our spirits so that we can live as spiritually healthy beings. This is done through both internal and external processes, stimulating our minds, bodies, and spirits through eating right, exercising, relieving stress, regular doctor visits, meditation, religious service, or any practices that might aid us in uplifting our önd. Besides the work put into this, remember also to have fun, to enjoy life and laugh as often as you can, for the Gods themselves love laughter and know that we must cherish this gift of life and celebrate it every day we are alive. Spiritual practice is not about being serious and moody all the time, it's about retaining your youthful exuberance and experiencing the world with a constant sense of wonder and joy. So take a bite from Idun's apples and embrace your life and your world and all of its mysteries, fears, and pleasures as if today were your last day on earth, and no matter how old you are you can always stay young at heart.