Writing in prayer and study.
I write out my Lectio Divina meditations as it helps me quiet myself, slow down, and focus on what God has to say to me in the Scriptures.
Also, in my spiritual studies I lightly underline while I read but my studies really come home when, after finishing each chapter, I summarize them in writing using a notebook I keep just for this purpose. It really helps my comprehension and memory. I’ll often add some written reflection at the end of my summaries when a topic has especially spoken to me.