66 days. But only if you're an average habit-changer.
Phillippa Lally and colleagues from University College London found that the range for establishing new habits was 18 to 254 days. The habits included going for a 15 minute run before dinner and doing 50 situps after morning coffee.*
How useful is it to know about how long it takes other people to establish a new habit?
Put it this way: If we are struggling, we're not alone and the figures tell us to be realistic. Starting new habits and changing old ones takes constant repetition and accepting setbacks as part of the journey. The researchers' advice: Aim to repeat the new habit every day, but don't worry if you miss a day or two. 'Be prepared for the long haul.'
How will you know when you've established your new habit? You'll say things like, 'I do it without thinking' and 'It's hard not to do it'.
Trying to extinguish a bad habit?
Notice that the new habits in the study involved a context or cue for the new behaviour '...before dinner' and '...after morning coffee'.
Change the context that prompts you into behaviours you'll regret. Don't store cheesecake in the fridge. Don't have cigarettes anywhere near coffee. Serve meals on smaller plates. Even eating popcorn with their non-dominant hand has discouraged people from devouring the whole boxful.
We heard of one man who wanted to give up smoking, so he changed countries. It's a bit drastic, but it changed the context. He wouldn't have been prompted by say, meeting up with his usual smoker friends, peer pressure, or the stresses at work that set him thinking about a cigarette.
*Study published in European Journal of Social Psychology (2010)