Use a Post-it-Note and leave it on the bathroom mirror (or tape and paper if you are short on sticky note pads).
Keep it short, and sweet is the word of the day. Sweet, not goofy or funny or hot-n-heavy. Just plain ol' sweet will do today.
Out of ideas?
Try one of these:
- "I already miss you!"
- "I will be thinking of you all day!"
- "The day will seem long until I can see you again"
- "You are the best thing that has ever happened to me. I love you"