The challenge of the day is to leave a little note for your loved one. It need not be something large or elaborate, but something special and dear to the both of you.
Place it somewhere it will be found as a surprise. There is no need to be obvious about it or to make a big deal (especially if this is something new for you). Just leave it where it will be found and let nature take its course.
Take time to make it as special as you can. If you have only a few minutes, then use them as best you can. If you have an hour, then pour a bit more of your heart into it. Perhaps a touch or scent or color will help.
Whatever you do, make it personal and offer it up with devotion and care.