rest on one's laurels

The laurel was Apollo's tree, and it came to him out of grief. He had chased the nymph Daphne through the woods, and rather than be caught she prayed to be changed; her running feet took root, her arms grew rough with bark, and her hair spread into dark glossy leaves. Apollo could not have her, so he took the tree for his own and swore its green would crown the greatest of mortals forever.

And so it did. At the Pythian games held in Apollo's honour, and later across the whole Greek and Roman world, the victor was not paid in gold but wreathed in laurel. To feel those cool leaves pressed to your brow before a roaring crowd was to be marked, for that day, as the best there was.

But a wreath is a strange sort of prize, because it does not last. The leaves that shone at the ceremony dry and curl within days, and the crowd that cheered soon turns to watch the next contest and the next champion. The honour was real, but it was tied to a single afternoon.

The danger, everyone understood, was the athlete who kept wearing yesterday's crown, the one who sat back on the strength of one victory, trained no longer, and let newcomers pass him. He was said to coast on a garland already going brown.

To rest on one's laurels still means exactly that: to lean on a win already won, as if a single old triumph could stand in for the work you have stopped doing.