Please ENjoy the trip as you move to a far away place on earth.
CULTURAL CODE WORD in full effect. Meaning, it's such a uniquely Japanese concept there is no ready English equivalent.
遠慮 means to be diplomatically, politely refuse, to regretfully decline.
For example, "You want the last donut?" "Hell yes!" is not 遠慮.
But, "No way I don't want it, it smells!" is also not 遠慮 .
"Thanks but I'm full now." is the 遠慮 answer, since it means, "We both know I want it, but since I abstained from it, you owe me one, now! The favor-ball is back in my court!"
Used most commonly in two situations：
1) 遠慮せず： meaning, 'Act casual. Eat the last pie. Don't wait for all the food to be served. Sit wherever. Make yourself at home.'
2) it's often seen on signs telling you not to do something: XXX遠慮してください。 ('Please refrain from doing XXX')
the poetic 'forever'： I'll hate you forever! We shall rule the world forever!