I tend to use these two:
Prayer of St. Thomas Aquinas
I thank you, holy Lord, almighty Father, eternal God, who deigned to feast me, sinful and unworthy servant, with the precious body and blood of your Son, Jesus Christ our Lord, not for any merit of mine, but only because of your merciful goodness. And I pray that this Holy Communion, far from condemning me to punishment, may bring about my pardon and salvation, encompassing me with the armor of faith and the shield of a good will. By it let my vices be done away, all lustful desires extinguished. May it advance me in charity, patience, humility, obedience, and every other virtue. Let it be strong defense against the wiles of all my enemies, visible and invisible, allaying for me every disturbance of flesh and spirit, binding me firmly to you, the one true God, and bringing my last hour to a happy close. I pray, too, that it may be your pleasure to call my sinful self one day to that banquet, wonderful past all telling, where you, with your Son and the Holy Spirit, feast your saints with the vision of yourself, who are true light, the fulfillment of all desires, the joy that knows no ending, gladness unalloyed, and perfect bliss: through the same Christ our Lord.
Amen.
THE UNIVERSAL PRAYER (attributed to Pope Clement XI)
Lord, I believe in you: increase my faith.
I trust in you: strengthen my trust.
I love you: let me love you more and more.
I am sorry for my sins: deepen my sorrow.
I worship you as my first beginning,
I long for you as my last end,
I praise you as my constant helper,
And call on you as my loving protector.
Guide me by your wisdom,
Correct me with your justice,
Comfort me with your mercy,
Protect me with your power.
I offer you, Lord, my thoughts: to be fixed on you;
My words: to have you for their theme;
My actions: to reflect my love for you;
My sufferings: to be endured for your greater glory.
I want to do what you ask of me:
In the way you ask,
For as long as you ask,
Because you ask it.
Lord, enlighten my understanding,
Strengthen my will,
Purify my heart,
and make me holy.
Help me to repent of my past sins
And to resist temptation in the future.
Help me to rise above my human weaknesses
And to grow stronger as a Christian.
Let me love you, my Lord and my God,
And see myself as I really am:
A pilgrim in this world,
A Christian called to respect and love
All whose lives I touch,
Those under my authority,
My friends and my enemies.
Help me to conquer anger with gentleness,
Greed by generosity,
Apathy by fervor.
Help me to forget myself
And reach out toward others.
Make me prudent in planning,
Courageous in taking risks.
Make me patient in suffering, unassuming in prosperity.
Keep me, Lord, attentive at prayer,
Temperate in food and drink,
Diligent in my work,
Firm in my good intentions.
Let my conscience be clear,
My conduct without fault,
My speech blameless,
My life well-ordered.
Put me on guard against my human weaknesses.
Let me cherish your love for me,
Keep your law,
And come at last to your salvation.
Teach me to realize that this world is passing,
That my true future is the happiness of heaven,
That life on earth is short,
And the life to come eternal.
Help me to prepare for death
With a proper fear of judgment,
But a greater trust in your goodness.
Lead me safely through death
To the endless joy of heaven.
Grant this through Christ our Lord. Amen.
