Here's one from the Fr. Lasance Prayer Book:


O Almighty God!  Whose wise and amiable providence watches over every human event, deign to be my light and my counsel in all my undertakings, particularly in the choice of a state of life.  I know that on this important step my sanctification and salvation may in a great measure depend.  I know that I am incapable of discerning what may be best for me; therefore I cast myself into Thy arms, beseeching Thee, my God, Who hast sent me into this world only to love and serve Thee, to direct by Thy grace every action of my life to the glorious end of my creation.  I renounce most sincerely every other wish than to fulfil Thy designs on my soul, whatever they may be; and I beseech Thee to give me the grace to be imbued with the spirit of Christ and to qualify myself for any state of life to which Thy adorable providence may call me.  O my God! whenever it may become my duty to make a choice, do Thou be my light and my counsel, and mercifully deign to make the way known to me wherein I should walk, for I have lifted up my soul to Thee.  Preserve me from listening to the suggestions of self-love, or worldly prudence, in prejudice to Thy holy inspirations.  Let Thy good Spirit lead me into the right way, and let Thy adorable providence place me, not where I may naturally feel inclined to go, but where all things may be most conducive to Thy glory and to the good of my soul.  Mary, Mother of Good Counsel, Seat of Wisdom, Help of Christians, pray for me.  Amen.

The prayer for "My Vocation in Life" from the "My Sunday Missal" published by the Confraternity of the Precious Blood in 1944:
Behold me at thy feet, O Virgin most kind, seeking to obtain through thee, the most important grace of knowing what I ought to do. I desire nothing but to comply perfectly with the Will of thy Divine Son at every moment of my life. Mother of Good Counsel, let me hear thy voice. It will dispel every doubt that troubles my mind. I trust in thee, being confident that, since thou art the Mother of my Redeemer, thou wilt also be the Mother of my salvation. If thou, O Mary, wilt not send me a ray of the Divine Sun, what light will enlighten me? Who will direct me if thou refusest, who art the Mother of the uncreated Wisdom? Listen, then, to my humble prayers. Let me not be lost in my uncertainty and instability; lead me along the straight road that ends in life everlasting, Thou, who art my only hope, and whose hands are full of the riches of virtue and of life, and who dispensest the fruits of honor and holiness.