It seems New Zealanders aren't doing too badly when it comes to how long we live.

A new book, called 'The Healthy Country', looks at the history and intricacies of life expectancy in New Zealand.

Co-author and health researcher Alistair Woodward says for a time in the early 20th century, we had the longest lifespans in the world.

He says even though that's no longer the case, we're still adding six hours to our average life expectancies each day.

Alistair Woodward says we're doing quite well on the world stage too - up to sixth longest lifespan for men, and gaining.

He says achieving some simple goals, like a smokefree society, will help even more.