St. Paul writes some ways that one can know that one is a person of God. I pulled some of the best bits together here so that it can be an example of how you can pull a prayer directly from scripture. This is a great section to consider during Lent.
3 We give no offense to anyone, that our ministry may not be blamed,
4 On the contrary, let us conduct ourselves in much patience...
6 in innocence, in knowledge, in long-sufferings; in kindness, in the Holy Spirit, in unaffected love;
7 In the word of truth, in the power of God; with the armor of justice on the right hand and on the left;
8 in honor and dishonor, on evil report and good report; as deceivers and yet truthful, as unknown and yet well known,
9 as dying and behold, we live, as chastised but not killed,
10 as sorrowful, yet always rejoicing, as poor yet enriching many, as having nothing yet possessing all things.
11 we are frank with you... our heart is wide open to you.
12 In us there is no lack of room for you...
16 For you are the temple of the living God, as God says, I will dwell and move among them.
So you could make yourself a card with this prayer:
O Lord, grant that we give no offense to anyone, so that our ministry may not be blamed. On the contrary, let us conduct ourselves in all circumstances as Your ministers, in much patience, in innocence, in knowledge, in long-sufferings; in kindness, in the Holy Spirit, in unaffected love, in the word of truth, and in Your power, with the armor of justice on the right hand, and on the left hand. Grant that we are acceptable to thee in honor and dishonor, in evil report and good report; as deceivers and yet truthful, as unknown and yet well known, as dying and behold, in your grace, we live, as chastised but not killed. O Lord guide us to be as sorrowful, yet always rejoicing, as poor yet enrich many, as having nothing yet possessing all things. In our ministry may we be frank with you, our heart wide open to you. In us there is no lack of room for you. For we the faithful are the temple of you, O Living God, as you have promised "I will dwell and move among you." In Your name, Amen.
See? This is how easy it is to take a section of the scripture, think about it and its message, and then write a very personal prayer using the very words of the saints, the prophets, the Lord himself. In this case we now have a lovely prayer using as its basis St. Paul's very words. What he has written as instructions to the faithful you can gently fashion into a beautiful prayer to God to help give and support you in those qualities that Paul listed for the Corinthians.