Ruby H Rose, nice question with some profound meaning!
I would answer this question by first explaining what I (and many others, especially those of the L.D.S. faith) understand is the correct definition of a "soul".
A soul is comprised of two parts, [our] spirit and [our] flesh (body).
Furthermore, one must understand that "all good things" come (directly) from God.
Therefore, when a soul is nourished, which is good, one can choose to attribute that nourishment as emanating from a loving Heavenly Father; or one can attribute their soul's nourishment as being a result of their own situation, devices, awareness, and actions.
I choose to acknowledge that my soul's nourishment comes from above.
To elaborate in a way others may find it easier to reckon as I do, let me refer, in a layman's way, to the Doctrine and Teachings of Jesus Christ. When one suffers a "spiritual death", per say, it merely means growing "distant" from God, turning from Him, or placing in one's life another strange god, master, or idol in replacement of Him that gives us breath and life. Of course, one can repent (turn back "to" God) and thus as a result, grow closer to Him in order to recieve more fully of His goodness/nourishment
So, without going into details of a self-righteous sort - of which I am not, an example of how I go about "effecting" the nourishment of my soul is to "pray" for this blessing in particular. I do this regularly, usually in silent privacy.
I may normally first thank Heavenly Father for my blessings (acknowledgement); then I express my gratitude with humility - knowing that I am unable to even produce the most simple blade of grass with my own wherewithal; then I ask Him to bless, for instance the meal I would consume, specifically and individually for the nourishment of BOTH my soul and my flesh.
I believe He hears me and I believe He has my wellness in mind, and because of my respectful petition to Him, I believe He does bless me in at least two ways - He ensures that my flesh remains healthy (sometimes even in spite of my foolishness), and He also specifically blesses my spirit (with a measure of His Holy Spirit). Thusly my soul is nourished, and I thank God for it.
Peace and Good tidings, Ruby H Rose.