Here’s how I interpret it: All human beings have lustful desires that need to be quashed. All human beings are inherently sinful, and it is only through vigilance that they avoid sin. There are many temptations to sin, and we need to be constantly wary of them.
In Donne's early years, he was something of a spirited young man: before he married, he seemed interested in wooing women and writing "conceits," poems that used unusual extended metaphors. He was not above trying to us these poems to woo a young woman into his bed with his unusual reasoning, as he writes in his poem "The Flea," which suggests to a woman that since they have both been bitten by the same flea and now share the same blood, they are as good as married. While his poetry changed after he married Ann More, his early poetry reflected the same attitudes of other writers like Andrew Marvel.
In this period of his life, his work reflected the desires of the individual more than anything else in pursuing individual physical satisifaction. However, when Donne ultimately joined the church in his later life, his concentration in his poetry (e.g., his Holy Sonnets) was focused on the individual establishing a closer relationship with God. In his Holy Sonnet 14, Donne calls on God to shape him into the man he should be, to put aside aspects of his life that are too closely tied to what the "enemy" wants, and break him in order to restore him in a new spiritual form. In both cases, Donne concentrates on the individual.
You might also like to think of the way that Donne's faith led him to often write about the importance of renouncing individual desire, especially in his religious poetry. An examination of his Holy Sonnets shows the way that so often he feels that individual desire is something that needs to be sacrificed as part of his much bigger and more earnest desire to pursue his relationship with God.
John Donne was not only a poet but a highly renowned preacher in the Anglican Church. His religious views were deeply ingrained in his mentality and psyche. As a result of his extraordinary attachment to and acuity of understanding of his religion's precepts, his love poetry unites expressions of individual desire, both physical and emotional desire, with religious expressions, for example, the union of the image of baring one's soul to God is coupled with the image of a woman presenting herself to her lover in “To His Mistress Going to Bed.”
One way to read many of the poems written by John Donne is to assume that nearly all the speakers he presents are motivated by personal desire of some sort. In the religious poems, the personal desire is often for love or forgivness from God. In the secular poems, including the Songs and Sonets [sic], the desire is often for love from another person. Sometimes the love desired and offered is genuine love (known in the Renaissance as caritas, or charity); sometimes the love desired and offered is selfish desire (known in the Renaissance as cupiditas, or cupidity). A case can be made that Donne's poems routinely mock cupiditas and routinely endorse caritas, either openly or by ironic implication. For a good statement of this approach to Donne, see N. J. C. Andreasen's book John Donne: Conservative Revolutionary. Hope this helps!