I had it after covid in March. It took 8 months, but I'm now back to normal (69 yo female who was an exercise fiend). Covid resulted in exercise-induced fatigue and cardiovascular problems. The cardiologist had me take baby aspirin to thin the blood (microclots). Check with a doctor first. I only did aerobic exercise in small bits with 20 minute rests between (short walks, cleaning...) and didn't start to ramp up workouts until a few months after covid and I was better. Resistence exercise didn't seem to be hit (weights are good for keeping muscle).

When you are tired, rest. Covid is a nasty disease and it is a waiting game. It helps if you get enough sleep, keep a food log (some folk get food intolerances after viral infections), stay hydrated, and try to escape mentally as much as you can (apocalypse movies not so good). Here are NIH and a PBS articles on long covid exercise intolerance: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10310058/ https://www.npr.org/sections/health-shots/2024/01/09/1223077307/long-covid-exercise-post-exertional-malaise-mitochondria