I think my first visit to Japan (FRA-NRT) must have been the worst, as my body, for whatever reason, simply refused to adjust to the time zone.

Never had that problem again afterwards. I usually have a body that adjust pretty well and fortunately jet lags are not things I am troubled with very often.

One thing I have learned, though, is that the more often I travel between timezones, the easier my body gets to it and the less jet lag or similar symptoms I face.