Write a love letter or e-mail. Don't worry that you're not a writer; just be simple and sincere, rather than trying too hard to be romantic. Describe how your partner makes you feel, and mention specific qualities you appreciate or quirks you find endearing.
Recall your past times together and describe your hopes for the future. And once a year, renew your commitment not only to your partner but also to keeping passion and intimacy in your relationship, maybe by taking a romantic getaway on your anniversary or celebrating with a once-in-lifetime event.