In discussing the spiritual disciplines of abstinence (solitude, silence, fasting, frugality, chastity, secrecy, sacrifice) Dallas Willard has the following to say,

“In the disciplines of abstinence, we abstain to some degree and for some time from the satisfaction of what we generally regard as normal and legitimate desires….  Keep in mind that the practice of abstention does not imply there is anything essentially wrong with these desires as such….  An adequate course of spiritual discipline will single out those tendencies that may harm our walk with God.  By the carefully adapted arrangement of our circumstances and behavior, the spiritual disciplines will bring these basic desires into their proper coordination and subordination within the economy of the life in his Kingdom.”

from The Spirit of the Disciplines: Understanding How God Changes Lives, pp 159 -160.