If any Christian man would be honest with himself, he might readily agree with me when I say that the sin of sexual lust just might be the "final frontier" in the lifelong process of mortification of sin. It has reduced many great men to loaves of bread (Prov. 6:26), the likes of which figure in the roster of those labelled as heroes of the faith. Can we mention the more prominent names, like Samson, David, and Solomon, and forget their trysts with unchastity? Arguably the greatest theologian since the Apostle Paul, Augustine himself is known to have been weighed down heavily by this struggle.
On the Reformation front, we read this of Huldrych Zwingli:
Zwingli apparently struggled early in life with sexual temptation. By his own admission he broke his vow of chastity on several occasions and often spoke of the shame that overshadowed his life. In fact, his appointment to the church in Zurich in 1519 was challenged based on rumors that he had seduced the daughter of an influential citizen. As it turned out, this "lady" had seduced many in Zurich, Zwingli among them. The charge of immorality was finally dropped when it was discovered that Zwingli's only rival for the post openly lived with several mistresses and had six illegitimate children! Zwingli himself lived with a widow, Anna Reinhart, and finally married her in 1524 shortly before the birth of their child. (Zwingli and Anabaptists)
Like many in his day, Zwingli's morals didn't always stand up to scrutiny. In January, 1519, a church called him to Zurich. When the call came, a young woman in Einsiedeln charged him with getting her pregnant. Zwingli admitted his guilt. In his admission, Zwingli said he made an early vow not to touch a woman but found it difficult to keep. He said, "Alas, I fell and became like the dog, who according to the Apostle Peter, turned back to his own vomit." He tried some self-justification by pointing out that the girl was not the daughter of a prominent citizen but the daughter of a barber. In those days barbers had poor reputations. He also said she possessed a poor reputation and had seduced him!
Perhaps impressed with his honesty, the Zurichers called him anyway. (The Zwinglian Revolt)
What all this tells us is that we, strugglers with lust, are in good company, the realization of which must not lull us into complacency but motivate us further into more vigilant watching and praying (Matt. 26:41) for "No temptation has overtaken you that is not common to man. God is faithful, and he will not let you be tempted beyond your ability, but with the temptation he will also provide the way of escape, that you may be able to endure it" (1 Cor. 10:13). The knowledge that our heroes' hearts were broken as much as ours on account of lust may just be one of these escape hatches.