No, you don’t ever have to pray over anything specific. In fact, comping up with words can sometimes be a “prayer blocker”, for a lot of people. This is why we have so many beautiful written prayers, and even the “basics”, although powerful, the Hail Mary and Our Father.
I usually suggest to my children and others a special type of prayer called “contemplative prayer”. It is very simple and very intimate. It is a prayer in which you imagine Christ, sometime a specific image like a Mystery, sight, sound, smell in complete silence. Sometimes in my deep sufferings I will do this, imagining I’m at the crucifixion, the smell if the dirt and blood, the sound of Mama Mary crying along with those who are present, things of that nature. Sometimes I imagine the nativity, or just simply the face of Christ, and I allow myself to feel adoration for Him.
I hope this helps you, I know it helps my children who often do not have the words in mind, and it helps me as well. Honestly in that silence you have an opportunity to hear God, and be comforted knowing He knows the troubles in your life.