We can all play our part and make better decisions going forwards. Simple changes. Buy less plastic—a Water to Go bottle saves ever having to buy a single use bottle. Take shampoo/conditioner/soap bars rather than bottles. Eat in local restaurants and speak to the people in local shops—it’s important that we are welcomed by those hosting us, and not intruding.
A bigger switch might be travelling by train around Europe. You might be surprised how little extra time it takes to travel by train across Europe. Or you could fly one way and take the train the other—that would help reduce your carbon footprint.
Making more conscious choices while travelling isn't about "having less" or "going without"; it's just about thinking before you buy, wasting less, being more efficient, eating local food, buying local crafts, trying a few words in another language.
If you want to learn a bit more we can thoroughly recommend checking out Jen Gale’s website, it’s all about being imperfectly green and making small steps in the right direction.