Here is another one, by St. Thomas Aquinas:
O good Jesus, I know that every perfect gift
And, above all others, that of chastity, depends
On the powerful action of your divine Providence;
I know that without You a creature can do nothing.
This is why I beseech You to defend, by Your
Grace, the purity of my soul and of my body.
And if I have ever received any impression
Whatsoever of a sentiment capable of soiling this
Ineffable virtue, O supreme Master of my faculties,
Blot it out from my soul, that with a clean heart
I may advance in Your love and in Your service,
Offering myself chaste all the days of my life
On the most pure altar of Your divinity.
It is the Cross that I adore. The Cross of the
Lord is with me. The Cross is my refuge. AMEN
And here is one to St. Thomas:
Chosen lily of innocence, pure St. Thomas,
who kept chaste the robe of baptism
and became an angel in the flesh after being girded by two angels,
I implore you to commend me to Jesus, the Spotless Lamb,
and to Mary, the Queen of Virgins.
Gentle protector of my purity, ask them that I,
who wear the holy sign of your victory over the flesh,
may also share your purity,
and after imitating you on earth
may at last come to be crowned with you among the angels. Amen.