Author of bestseller Psycho-Cybernetics, Maltz was a reconstructive and cosmetic facial surgeon. He moved from treating `outer scars’ to `inner scars’ after observing that some people were still unhappy with their new faces, claiming they didn’t feel any different even though their appearance had changed.

Maltz tried to find out why this was happening. He discovered that your 'outer life' was a reflection of how you saw yourself on the inside, what he called 'self-image'.

From further observations Maltz found it took at least 21 days to create a new habit. Since then the '21 Day Habit Theory' has become an accepted part of self-help programmes.

Brain circuits take engrams (memory traces) and produce neuro connections and neuro pathways only if they are bombarded for 21 days in a row. This means that our brain does not accept a change of habit unless it is repeated each day for 21 days (without missing a day).

The idea is simple, but the trick is in the determination to keep with it for the 21 days. The old habit does not leave you, it is simply replaced by the new habit.