Perhaps they'd followed her lead and begun to kiss their partner more regularly, or cleared clutter from their homes, or took a 20 minute walk each day. Simple things that had helped them lead a happier life.

"But more often there was something they couldn't do which was frustrating them ... they'd be like 'Why am I so exhausted, why can't I get anything done' and I began to realise that what they were talking about were habits.

"They weren't thinking about it like that though, they weren't thinking 'Why can't I form the habit of going to bed on time, or why can't I form the habit of working steadily on a project' Was working on changing habits the answer?"

And so her latest book Better Than Before: Mastering the habits of our everyday lives evolved. Its premise is if we change our habits, we change our lives.

"For a happy life, it's important to cultivate an atmosphere of growth – the sense we're learning new things, getting stronger, forging new relationships, making things better, helping other people.

"Habits have a tremendous role to play in creating an atmosphere of growth, because they help us to make consistent reliable progress."

Rubin realises that some people find it easier to shape habits than others. She herself loves habits, embraces them and is good at forming them. She thought, initially, that everyone was the same.

"I kind of had to rewrite the whole book once the light dawned. When I started writing I had no framework to compare people, just an assumption that people were basically the same in their aptitude or attitude to forming habits. Once I developed my framework I realised I'm an extreme, tiny category, on the freaky fringe, an upholder – which came as a surprise to no one but me – it explained a lot why I was actually writing a book about habits."

She said once people identify which tendency they belonged in – upholders, questioners, obligers or rebels – the framework for shaping lasting habits became easier. From there it was a matter of monitoring habits, of scheduling them, of working out whether you were better off taking big steps, or small steps towards a goal.

When is the best time to start a new habit? Tomorrow, your birthday, the first of the month?

"Now," Rubin says. "But now is an unpopular time to take a first step."

One reason, she says, is because it's human nature to seek loopholes.

"This was one of my favourite chapters, I have a thousand examples of loopholes.

"I know I'm trying to lose weight but I can eat this cake because it's my birthday and I've been good, and I'm going to start again tomorrow, and after all you only live once and what's one day and this is the only chance I have to eat this kind of food.

"The trick is to catch yourself invoking the loophole and stick to the habit."

Rubin describes herself as someone who writes about human nature. One of her first books was Power Money Fame Sex: A User's Guide, a social commentary in the guise of a how-to manual. She's also written biographies of Winston Churchill and John Kennedy. Her books Happier at Home and The Happiness Project were both instant New York Times bestsellers, and have sold more than 2 million copies in 35 languages. She lives in New York, with her husband and two daughters. On her website gretchenrubin.com she writes about her adventures as she test drives ideas from contemporary science and ancient wisdom about building good habits and a happier life.

She says it's important to keep striving for a better life, for happiness.

"You don't get better if you don't keep striving for better," she says.

"It's OK to say perfection is not your aim, you just want to do better, but you're not going to hit a target if you're not aiming for it.

"If you want something it's not going to happen unless you make an effort.

"But ask yourself if what you're doing is working for you, is there a need to change it?"

▪ Better than Before: Mastering the habits of our everyday lives, by Gretchen Rubin. (Hachette, $16.99.)

▪ Gretchen Rubin will speak and hold workshops at Happiness and its Cause forum in Sydney on June 10-11. Other speakers include His Holiness the Dalai Lama, Robert Biswas-Diener and Ruby Wax. happinessanditscauses.com.au/