Why is it that when I travel, everyone I travel with thinks it’s fun, but I’m not happy at all? Is it my problem?

The meaning of travel lies in the process rather than the destination. You are the opposite, critical of the process but disappointed in the destination. So everyone is happy and you are alone in depression.

What needs to change is yourself, how to integrate into the group, and how to draw highlights from the ordinary. In addition, it seems that you need to exercise more, because traveling is also a challenge to your physical strength.