Microwave change heats fast and cools fast. Slow cooker change is the one you’re still tasting next week.

Fast change and lasting change use different mechanisms. Anything that transforms your life in a fortnight is running on novelty, and novelty has a short half-life, so the collapse arrives roughly when the excitement does. Slower change works because by the time you notice it, it has stopped requiring a decision.

When you are choosing between an intense plan and a modest one, pick the one you would still be doing in March. The modest version looks unambitious now and is almost always ahead by summer.