Keep the reason and shrink the first step
Write down what the habit is for, and keep that apart from how big the habit is. If the goal is to read more, one page keeps it alive on a hard day. If the goal is to move, a two minute walk counts.
A good small version lowers the effort it takes to begin. It should still feel worth doing.
Remove one obstacle before the moment comes
Put the book where you sit. Lay out the shoes. Leave the document open on the next paragraph. When the first action is obvious, you don't have to plan the whole thing again each time.
If starting is the hard part, make the first action take less than a minute. You can decide whether to keep going once you've begun.
Move it when the week is full
Sometimes the habit is fine and the time is wrong. Try another anchor in the day, or do it less often for a while. Avoid make-up sessions that overload the next day.
Change one thing at a time and give it a few tries. That way you can tell which change helped.
Make the smaller version official
Give the habit a named minimum, the version you do on a hard day, and decide that it counts. Then a busy day has a clear option besides skipping.
In LilCoach every habit has a minimum. On Today you swipe a habit left and tap Minimum, the day counts, and your history shows it was the small version.
How the minimum works in LilCoach
Look at what happened before deciding
After a few tries, ask yourself whether it was easier to start, whether the time fit, and whether the smaller step still felt useful. Keep the version that helped you come back. If it still doesn't fit, try another small change.