How do you get out of lethargy?

Underlying cause. First step is identifying what's causing the lethargy. Hormones such as thyroid? Depression or sleep disorder? Poor eating habits? Alcohol overuse? Diabetes, blood pressure, infection? Start with your Family Doctor. Good luck. .
Exercise. Exercise and eat fresh fruits and vegetables. Also talk to your family physician, you may be suffering from obstructive sleep apnea or possibly hypothyroidism.
Find & Rx cause. Chronic fatigue syndrome is a multifactorial consequence of hormonal, immune system and nervous system dysfunction resulting from genetic predispositions and dietary and environmental insults. These factors impair the patient's ability to produce energy and they end up chronically fatigued. There are numerous internal & external stressors that can contribute to this syndrome. Find & rx.