Traveling across several time zones doesn't have to upset your routine.
In flight, keep exercising your legs with clock wise and counter-clock wise leg rotations. Or get up and move around as much as possible.
Drink plenty of water...not alcohol or caffeine. Dry air in the plane's cabin dehydrates you more than you realize.
Try to sleep. Ear plugs, eye covers and a warm blanket helps.
Eat...but in small quantities.
When you land, stick with your daily routine. If you exercise at 10 am or take a warm bath at 8 pm...do it at your destination and acclimate your body to the new time zone.