Why is spirituality necessary? In part, to correct the unexamined idea that there is only one growing up in life, whereas there continue higher levels of our apprenticeship to maturity, whereby there is the second growing up, the third growing up, and so forth. There needs to be something higher towards which we aim and strive. Just as when we were children, we needed the model of adults in order to grow, so as adults we need models of something higher as well.
There are certain skills you need to know and assimilate to function in the adult world, but it is a great mistake to think that your learning has stopped here. In fact, many adults assimilate these practical skills while remaining quite immature on other levels. To round ourselves out fully, in other words to become whole, takes time, effort, and commitment, as well as the consciousness that the journey is not yet over and there is still good work to be done, noble goals to strive towards even in our stumblings.
In the old culture, there were three levels plus a higher fourth : childhood, adulthood, and elderhood, followed by the status of ancestorhood. At each stage there were difficulties to assimilate and challenges to overcome. Compare this to our secular society of essentially two stages, childhood and adulthood, as if one was then done. The old culture's stages on a personal level were then mirrored historically and sociologically : Thralls, Carls, and Jarls, above which were the Gods. Just as an elder ought be listening to the ancestors for guidance, so ought nobles be listening to the Gods for guidance.
By having these levels, there is constantly something to strive towards, and good work to be had. And one should never underestimate the value of good work, which nourishes and strengthens.
Each stage is ideally striving to be like or become the next stage (while also enjoying the process of the present, with all its joys and flavors) : a child strives to become an adult, an adult strives to become an elder, and an elder is learning how to become an ancestor. Likewise, those in debt to the community try to free themselves in order to become good, decent members of the community with a sense of dignity, those who are free and decent strive to ennoble themselves, and those who are noble strive to reflect the divine within their lives, all in good time, all with the long time it takes. Of course, Heimdall's blood runs through them all, but those who have worked the hardest and achieved the fullest receive the greatest of the mysteries.