What is what does it mean to rest on your laurels?

Resting on your laurels means to be content with your past achievements and to stop making an effort to improve or achieve more. It implies a decline in ambition and a reliance on past successes instead of striving for further progress.

Essentially, someone who is resting on their laurels is:

The phrase comes from the ancient Greek custom of awarding a laurel wreath to victors and heroes. Metaphorically, the "laurels" represent past successes, and "resting" on them means being satisfied with those successes to the point of stagnation. (https://www.wikiwhat.page/kavramlar/Past%20successes)