Before penning down my msging to woodblock, thought of seeking some help/reference online:

To help you get started, try a vow writing exercise for inspiration. Think about the wonderful times the two of you have spent together. Write as much, or as little, as you feel.
1. I love my partner because.............
2. Marriage means the following to me............
3. When I realized I was in love, it felt like..............
4. One of our favorite songs is ........................
5. My partner made me laugh so extremely hard when...........
6. Write down any nicknames you call your partner.................
7. The following adjectives describe my partner...............
8. My partner has taught me................
9. My partner inspires me to.....................................
10. The kindness/ love/ generosity shown one time by my partner that I will always remember how it touched my heart deeply was.........Once you are finish reading your answers to each other, choose a few of your favorite words or phrases and start writing your wedding vows:I, ........., choose to have you .......... to be my........... from this day forward because............You will be deeply moved by what you hear from each other. Now that's an exceptional wedding ceremony and a day to remember!

Source:http://www.streetdirectory.com/travel_guide/55543/wedding_bells_/eloping_made_special_with_inspired_wedding_vows.html