In most parts of the world the answer is Yes. I encourage you to write, or at least choose, your own marriage vows. You may select traditional or contemporary vows or have a blend of both. You will need to confirm with your own celebrant if they are happy to allow this.

With regard to the legal vow, The Marriage Act 196 - section 45 (2) states that each party must say to the other, in the presence of the marriage celebrant and witnesses the words: 'I call upon the persons here present to witness that I, AB (or CD) take thee, CD (or AB) to be my lawful wedded wife (or husband)' or words to that effect. Your celebrant can advise as to other suitable wording to that effect.

HINT - If you want to know how to write your own vows, my book, 'Create Your Own Inspiring Wedding Ceremony' takes you through the process step by step and is available in hard copy or as an eBook (pdf download). It has many wonderful examples of what you can do as well as choices on how your vows can be delivered on the day. You can find out more about the book and how to get hold of a copy here.