It depends on your attitude
If you mean that on vacation you don't mind about eating and you happily enjoy it... well, keep on not worrying
enjoy your vacation and when you come back, IF you will have gained weight (it's not for sure!) take it as a challenge... you know how to lose weight, and I see you are also quite thin too
If, instead, you mean that you can't control the food-situation... well, don't put too much pressure on you
... just try to, step by step, little by little, to choose everytime the healthiest option, with some treat here and there! I know that sometime there will NOT be a healthy choice at all... but after all, you are on holidays
Just try to limit the damage!