Surprise them with a hug from behind while they are busy doing something
Kiss them when they are in the middle of a sentence
Send them text messages throughout the day
Call them up on the phone and say nothing but I Love you
Write I Love You on a piece of paper and put it in their pants pocket while they are taking a shower
Go to a museum together
Take a long drive in the country
Put a flower on your their pillow
Send flowers to them at work. Make them feel special in front of others
Make up a secret code and page them with it all day
Call in to work sick on the same day
Buy a gift for them every day for a week
Hold hands
Take a long bath with lots of bubbles
Leave a trail of rose petals from the door to your bedroom for them to follow
Enjoy Champaign and strawberries together
Buy them some nice cologne/perfume
Start/end every day with a kiss
Rent a paddleboat
Run your fingers through their hair and speak softly to them while they fall asleep
Dedicate songs on the radio them them
Grab a lunch to go and sit on the grass at the beach/bay/lake
Light candles all around the house and have a little romantic music going for them when they get home