They only look it
What we see as tired eyes are often "puffy" eyelids that have dark circles under them. This can be the way your eyelids naturally look, or they could slowly take on this appearance over time.
Excess eyelid skin, especially on the upper eyelids, can make the eyes appear more closed. There may be treatment options for this, so if it bothers you, consider meeting with an eye doctor to discuss it.