Progress visualization of a person’s self-development?

I'm talking about any kind of self-improvement that is monitored/tracked. Most common example are fitness trackers or apps.

Now are there any guidelines or examples on this?
How would one best visualize the progress of the user over time, so that it will help him/her reflect upon it?

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Context

In my specific case it's about mental improvement (self-affirmation, confidence exercises and stuff like that). So participants have a main goal and finish certain steps on the way towards it.
The data I'll have will most likely be number of finished steps, distance to reaching the goal, self-reflection entries and possibly other ways.

The process is supposed to happen over approx. 3 weeks, with the user finishing a "step" approx. every 2-3 days and getting a new one then.

Since self-reflection is a crucial part of such a mental improvement process (Paper1 & Paper2) I really want to present the data in the most helpful way possible.