The Transtheoretical Model describes personal change not as one decision but as movement through stages — and people usually loop through them more than once before a new pattern sticks. Developed by James Prochaska and Carlo DiClemente from studies of smokers who quit without treatment, it maps where you are with a habit you might be changing — drinking, smoking, or other substance use — from not yet considering it, through weighing it up and preparing, to acting and maintaining the change. Naming your stage is the starting point of motivational, non-judgemental approaches to change: there is no 'behind', only where you are now.
The Transtheoretical Model's Stages of Change (Prochaska & DiClemente, 1983; Prochaska, DiClemente & Norcross, 1992) is a widely studied, validated model of how people change health behaviours such as smoking and drinking, developed from research on how smokers quit on their own. (Transtheoretical Model / Stages of Change (Prochaska & DiClemente))