Forming a habit is trying to form a cue-behaviour link in your memory, meaning you perform the behaviour without intentionally having to make yourself do it.

Cues can be internal or external (for example, feeling hungry or making a cup of tea) and are most effective when encounter...

Narrow down what you want to do. You need to have a specific plan to work out exactly when and how you’re going to do that.

A behaviour is more likely to become habitual if it’s something you enjoy or find rewarding. 

We are more likely to create a habit when it connects to our sense of identity.

Some habits are representations of certain important goals or values. If you manage to link certain behaviours to your sense of identity, it might help to establish those habits.

Make use of what we called ‘habit discontinuities': moments when people go through life-course changes, such as moving house, starting a family or a relationship, divorce, retirement or organization changes.

These kinds of events disrupt old habits and allow you to create new ones.

The widespread assertion that forming a habit takes 21 days is not true. Forming a new habit takes on average  66 days, with some people taking as much as 254 days (and some only 18).

And don’t despair if you miss a day. Just don't make a habit out of it.