Your first solo trip, even a day trip, teaches you that you can be your own good company.

Going somewhere alone teaches what cannot be read about, which is that you can manage a day on your own judgment. You pick the train, you get something wrong, you fix it, you eat when you want, and by the evening you have evidence rather than theory. It does not have to be far or long. Even a day somewhere new counts.

Plan one this month: a train to a town an hour away, a day at a place you have not been. Tell someone where you are going, take enough money, and leave the itinerary loose. Being your own company for a day is the whole point.