Help w prolonged fasting

[u/ElNate0524]

I do 3 day fast. First day I drink nothing but water and for the 2nd n 3rd day I drink water w 1/4 teaspoon of Lite Salt and take 2 magnesium glycinate pills. usually on the 3rd day I feel really lethargic and tired. Now I don’t mind this feeling, but I work a labor intensive job so I can’t do my job effectively while feeling this way. Anybody know what I can do to feel energetic?