This may be too late to implement, but then again, maybe not for those who still need suggestions. I just recalled that I had great success this year, when I wrote this attached letter to the parents (and family members) asking them to write an encouraging letter/message/note to my student which would be kept in a sealed envelope until the morning of our first state test. Parents wrote them and sent them in the week before.
With the letter to parents, I allowed my students to select a page from among the various types of stationery papers I had. They also decorated the outside of a plain white envelope. So, clipped together were: The parent letter, a sheet of stationery and a decorated envelope.
It was amazing to see the faces of my students as they read their parents loving words of encouragement and support! In many cases, students asked for messages from grandparents, siblings, as well as from parents. I think one student even asked the neighbor to write a few words!
! I asked permission from random students if I could read their pages and some of them brought me to tears! (There were a few students who did not return a message by the first day of testing, but once the others saw what they were missing, they brought in their notes the following morning.) Now that we're finished with testing, I told my students to save that page and refer to it whenever they are feeling a bit down and want to feel encouraged.