How to work all day long without tiring ? [w/o drugs pls=.=]
Get a good sleep and eat a healthy breakfast
Get a good night's sleep and eating well (healthy foods such as carrots, grapes, apples, bananas, etc.)
You can't. Fatigue is normal. Working all day long makes you tired. As Adrian^^ says , a good diet and plenty of sleep will help you to recover so you'll get up ready to do it all again.
Stay hydrated. Drink lots of water.
More rest, eat more vegetables