It is important to say from the get go that you had a career break. Explain why you took it and why you want to come back.

If you are returning to the same career, say you can not wait to return to what you love doing. If you are embarking on a new career, emphasis how you are excited about the new challenge. Be clear that you know this is what you want to do and that you have fully considered it.

If you can start immediately, make sure you include that in your cover letter too.