The Vilna Gaon, tzt"l, testifies (Even Shlaima ch. 2, part 10): "All pleasures which the morally corrupt may obtain with effort and exertion through forbidden avenues are granted to the wholesome, clean-living individuals in a permitted manner without any effort on their part." We lose nothing by choosing to keep our eyes clean and pure.
Yosef Hatzaddik married his bashert, Osnas. Together they raised a family of sons whom, till the end of time, countless Jewish fathers and mothers bless their own sons to emulate - Ephraim and Menashe, each to become a tribe in his own right. And Yosef Hatzaddik became the symbol of one who remained unbowed and unconquerable.
The Mesilas Yesharim writes (ch. 1) that every mitzvah elevates the whole world, while every forbidden act brings harm not only to the sinner but to the whole world. Therefore, every time you overcome temptation, you are bringing into existence a spirit of purity and holiness that benefits us all.
The Chida writes (Nachal Kidumim, Bereishis) that if Yidden look at forbidden sights, then the forces of Eisav and Yishmael gather strength. But if we take extra care to protect our sense of sight, then Eisav and Yishmael will be wiped out and Mashiach will come.
The call goes out to every Jewish man and woman to rise up and build a wall against that barrage of hollow filth. Though tznius may seem a hopeless anachronism, old fashioned and out-dated, by dint of our unflagging drive for modesty and purity in today's world of applauded and sophisticated hefkeirus, we will rise to pre-eminence, being princes and princesses. This is the fight at the End of Days. It's the tug-of-war for the holiness of Jewish eyes, after which we will take center stage, crowned with the glory of our King Himself.
The Midrash (Tanchuma, end of Vayigash) compares the happenings of Tzion to the life of Yosef. Rav Don Segal notes that just as Yosef earned kingship by dint of his undefiled eyes, so too Yerushalayim's meteoric return as spiritual capital of the world will be preceded by trials centered mainly on guarding the purity of Jewish eyes.