Hebrew Transliteration: "Ish Ki Yidar Neder La'hashem Oh Hishava Shevuah Le'esar issar al Nafsho, Lo Yachel Divaro, Kichol Hayotzeh Mi'piv Yaaseh".
English Translation: "A Man who makes a vow to G-d or an oath to forbid forbidden unto his soul, shall not make his words empty, like all that left his mouth he should do".
Normally making vows is frowned upon by our sages as with someone playing with fire, but when it comes to girding oneself from sexual temptation we find that making vows are praised by the Torah and by Chaz"al. As the Pasuk says "Nishbati Va'akayeima, lishmor Mishpatei Tzidkecha" - "I have vowed and will uphold, to guard your righteous laws". And also it says "Nishba Lehora Velo Yamir - Oseh eileh lo Yimot Le'olam" - "He who swears on evil and does not nullify... he shall never falter". And Chaza"l also say that Bo'az swore to guard himself from transgression when Ruth came to him that night, as it says "Chai Hashem, shichvi ad haboker" - "In the name of G-d (a type of vow), lay here until morning".
Vows are indeed one of the most powerful tools for a believing Jew to use to help hold himself back from the things that he knows often bring him to fall. One must be very careful though, to make only vows he knows he can fulfill. For example, always make vows for short periods of time at first, and then extend the period slowly, as you become more confident. See this page for advice on how to use vows in the safest ways to help you in these struggles.