I often find that much of this is mind over matter. If I come off a longhaul and take the day off, I feel like a zombie at home and just end up feeling generally ill. On the other hand, I tend to be able to keep going if I go to work- but you will "hit the wall" at some point. A few tips:
-don't pig out on the plane. If possible, eat pre departure and post arrival. Just drink water on the flight.
-have a shower and coffee on arrival if arrivals is still open and get changed
-when you hit "the wall", go outside in the "fresh" air etc and wash your face (!)