If you’re feeling unwell during the trip, let your Group Leader know as soon as you can. They can help point you towards a local pharmacy, doctor or other medical support if needed.
If you need to sit out an activity or take some time to rest, that’s absolutely fine. Your Group Leader will help you understand the plans for the day and when and where to meet back up with the group.
This is also one of the reasons suitable travel insurance is so important, as any medical treatment or related costs will normally need to be covered by you or your insurer.