13. Observe their posture
You can tell a lot about someone’s self-confidence by how they carry themselves. For example, if someone walks upright with their shoulders back and their gaze straight ahead, it indicates that they are confident and happy with themselves.
Slouching over and staring at the ground while walking, on the other hand, provides a completely different impression. It doesn’t always mean they have poor self-esteem, but that’s usually the message it gives off.