"But despite their common pattern, desires are not monolithic. Each offers a different perception of what's lacking in life, together with a different picture of what the solution should be. A desire for a sandwich comes from a perception of physical hunger and proposes to solve it with a Swiss-on-rye. A desire to climb a mountain focuses on a different set of hungers — for accomplishment, exhilaration, self-mastery — and appeals to a different image of satisfaction. Whatever the desire, if the solution actually leads to happiness, the desire is skillful. If it doesn't, it's not. However, what seems to be a skillful desire may lead only to a false or transitory happiness not worth the effort entailed. So wisdom starts as a meta-desire: to learn how to recognize skillful and unskillful desires for what they actually are."
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"What made the Buddha special was that he never lowered his expectations. He imagined the ultimate happiness — one so free from limit and lack that it would leave no need for further desire — and then treasured his desire for that happiness as his highest priority. Bringing all his other desires into dialogue with it, he explored various strategies until finding one that actually attained that unlimited goal. This strategy became his most basic teaching: the four noble truths."
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Sutra text: "What is right effort? There is the case where a monk (here meaning any meditator) generates desire, endeavors, arouses persistence, upholds and exerts his intent for the sake of the non-arising of evil, unskillful mental qualities that have not yet arisen... for the sake of the abandoning of evil, unskillful qualities that have arisen... for the sake of the arising of skillful qualities that have not yet arisen... for the maintenance, non-confusion, increase, plenitude, development, and culmination of skillful qualities that have arisen. This is called right effort."
As for the enlightened being:
"The Buddha encouraged these queries by describing the awakened person as so undefined and unlimited that he or she couldn't be located in the present life or be described after this life as existing, not existing, neither, or both. This may sound like an abstract and unreachable goal, but the Buddha demonstrated its human face in the example of his person. Having pushed past the limits of cause and effect, he was still able to function admirably within them, in this life, happy in even the most difficult circumstances, compassionately teaching people of every sort. And there's his testimony that not only monks and nuns, but also lay people — even children — had developed their skillful desires to the point where they gained a taste of awakening as well."
For more on this, Desire & Imagination in the Buddhist Path - the quotes above are extracts from that essay by Thanissaro Bhikkhu.