Prayer can take on various forms and be said or thought at various times. I love to pray and sometimes wonder in amazement how awesome God really is. Sometimes a certain scripture will capture your thoughts and other times it might be something someone said or did. Being grateful to God and how he awesome he is can sometimes be shown in art rather than words.
If you take the time to write down a scripture or prayer request and reflect on it you become more aware of what you really are asking God to help you with and how he might be answering you in different ways than you expect. Keeping them all in one place in a journal or sketchbook is a private place you can always go to.