The Change Curve
One theory that I use to help me support people through change is the change curve.
Here is a short explainer on what it is and how I use it (less than 5 mins).
My key advice:
It is important to listen and not overload people with information when they are early on in the change curve
Individuals will go through the change curve at different speeds
You can help people progress through the change curve by involving them in the change