How to keep a workout promise past the first month

Most workout promises die because they are too big and too far away. "I will get fit this year" has no deadline you can miss on a Tuesday. A promise you can keep has three parts: a short window (one week), a small number you can always hit (one to three sessions), and a cost for skipping that you feel today, not in March.

Make the cost go somewhere good. If a skipped session only hurts you, it is easy to forgive yourself on a tired evening. If it means money moves to a charity you chose, the miss still does something useful, and you have a reason to show up that is not only about you.

A week is long enough to absorb a bad day and short enough that every week is a fresh start. You never carry a failed January into February: Monday resets everything.

Promise fewer sessions than you think you can do. Two you always keep beat five you keep half the time, because the habit is built by keeping the promise. Extra sessions are welcome; they are just never required.

Decide when and where in advance. People who write down when and where they will act follow through far more often than people who only set the goal (Gollwitzer & Sheeran, 2006, a meta-analysis of 94 studies). Put the week's sessions in your calendar on Sunday night.

Money on the line works, and the effect outlasts the money: gym-goers who staked their own cash kept exercising at higher rates long after the incentive ended (Royer, Stehr & Sydnor, American Economic Journal: Applied Economics, 2015). Smokers offered a money-at-stake contract were more likely to quit (Giné, Karlan & Zinman, 2010).

The stake should be small enough that you could afford to lose it and large enough that you would rather not. One flat amount per week, never per session, keeps a bad week from escalating.

GoodEitherWay is a Norwegian app built on exactly this. You commit to one to three exercise sessions per Monday-to-Sunday week, with one flat 100 kr stake on the whole week. Do every session and you pay 0 kr. Each session gets a quick proof photo that only you can see. Nobody reviews it: the promise is with yourself.

Nothing is even held on your card unless you are still short on Thursday. Finish before then and GoodEitherWay never touches it. Miss a session and the whole 100 kr is donated to the charity you picked (in Norway today, Make-A-Wish Norge). The charity pays our 20 kr fee out of it, never you.

GoodEitherWay never tells you which exercises to do. Your checklist is yours: a run, a class, a swim, a long walk with the dog. You decide what counts.