There will be national clinical trial on the use of "Pacing" to manage PEM. Here is a link to the announcement of the trial:
https://trials.recovercovid.org/documents/RECOVER_ENERGIZE_Brochure_StructuredPacing_V1.0.pdf
Here is a link to a website with instructions on how to do "Pacing."
https://longcovid.physio/pacing
The study site where I'm in the RECOVER-VITAL clinical trial has applied to become a site for the RECOVER clinical trial of Structured Pacing. (Endeavor Health, Evanston, IL) I hope to participate in that study. In the meantime, I'm keeping a log of my periods of Activity and periods of Rest, and getting increasingly sensitive to internal sensations indicating when I need to end a period of Activity, and turn to Rest.

Also, see the comments under the Posting on this website about the RECOVER clinical trial.