Irreversible, chronic fatigue is a prominent symptom in many neurological conditions. I investigate such fatigue in stroke survivors. In the first part of my talk, I will first put forward a model of fatigue based on the active inference framework of sensorimotor control and then present neurophysiological, behavioural and perceptual data that corroborates the proposed model of fatigue. In the second half of my talk, I will discuss a new implicit measure of perceived effort. I will also present preliminary data from ongoing studies in stroke survivors and discuss how there may be a disconnect between explicit and implicit effort perception in stroke survivors with high fatigue.