Activity: Leave a note that says 'I love you' on the bathroom mirror or on car or anywhere else that she will see it when you're not around.
Another really easy one that only takes a minute. I got home before her and went and taped a note to her bathroom mirror. I then went and started cutting the grass. She got home while I was cutting the grass. After I was done I noticed that she seemed more affectionate than normal. Then later that night while we were laying in bed she said "Thank you for that thing on the mirror. What made you do that?" I replied "I just had to tell you that I loved you." She then said "Well, thank you. You need to do things like that more often." Little does she know I have about 27 more days of things like that planned.
So far so good.