An extremely healthy strategy to adopt is — eating in moderation and breaking down your food and fluid intake. Overeating leads to abdominal discomfort by putting more pressure on your digestive system at once, causing high levels of lethargy.
The main purpose of suhoor is to provide you with enough energy to survive the day. Missing that will leave you exhausted, until you eat again. But, a heavy meal will cause you to feel sleepy, so have a light meal with lots of fluids
Exercise is extremely important although it can be a real challenge at times. Your productivity will take a top-notch if you do light exercise, as it improves digestion and boosts your energy levels. Inactive body loses the momentum to keep going, making you sluggish and tired quickly.