The engine is tuned, but
fuel is low. Mix in
Active Recovery. Keep high-intensity training minimal.
Like a car, if you press your gas hard: you will run out of fuel quickly. After your Fuel is gone, you will start overtraining, so be careful.
In this real world example: Coach Cal suggests keeping the workout to under an hour with warmup. Take out planned High-intensity training and replace it with some rehab exercises, for known weakness. Running out of Fuel during the workout should be obvious.