When you travel through time zones, your circadian rhythm—the body's internal clock—can get disturbed. The newly introduced cycles of light and darkness along with times and functions like eating trigger responses that are contrary to the body's natural cycle. In short, it's a drag. But it can be alleviated.
In the days before your flight, shift your bedtime by an hour (or two) in the direction toward your upcoming time zone. Dehydration can intensify jet lag, so while you're waiting to board, drink at least 16 ounces of water.
As soon as you're on the plane, set your watch to your destination time. The quicker you start wrapping your mind around the new time zone, the better. If you're planning on sleeping during the flight, eat a handful of dried cherries 30 minutes before you'd like to fall asleep. According to nutrition expert Dr. Russel Reiter, the fruit is packed with natural melatonin—which is much gentler on your body's system than any pills that knock you out. When it's "morning" in your destination, open the window or turn on the light. Keep drinking that water, avoid alcohol and eat lightly.
Try to avoid crashing at the hotel. A quick 20 minute nap (if needed) is okay but anything more will interfere with your nighttime sleep. You can pop some more dried cherries before bed and in the morning, get your blood pumping with 10 to 20 push-ups before showering.