Poets known for their love-filled lyrics, such as Elizabeth Barrett Browning and Edna St. Vincent Millay, can help you communicate the love and adoration you feel for your boyfriend. If your boyfriend is a music lover, consider using romantic lyrics from a song you both like. Quotes on love from famous thinkers and philosophers such as Ralph Waldo Emerson can help you communicate the depth of your feelings for him.

Focusing on your shared past and the hope for a shared future can help show your boyfriend how you value his place in your life. You might reminisce about a trip you took together or the day you both first said "I love you," then write about how excited you are to share the next year and how glad you are to know he'll be by your side for any coming life changes. Tell him you hope to celebrate many more birthdays and make even more wonderful memories together.

If your boyfriend is fun-loving, use humor to show him you care. Purchase a birthday card with a short, humorous anecdote or make your own; use a funny picture of the two of you and add a silly caption to make him laugh. You could also draw a picture of the two of you doing some outlandish activity together and provide a caption like, "Happy birthday to the best boyfriend in the world, my partner in crime."

Sentimental, romantic thoughts on your boyfriend's birthday can show him how special he is and how in love you are with him. Tell him he is the love of your life and the best thing to ever happen to you. Use flowery language to describe his attributes that you admire and tell him that his smile makes your knees weak. You could also tell him that you're excited and grateful to celebrate the birthday of someone who has given you so much to be happy about.