Rest/sit on your laurels
Definition 1 of 1
Pro Tip 1/3Idiomatic Origins
Originally from ancient Greece where winners got laurel wreaths as a symbol of victory. 
After his novel won the prize, he was warned not to rest on his laurels.
Pro Tip 2/3Motivation Warning
Used to remind successful people to keep working hard and not become complacent. 
She has several bestsellers but can't rest on her laurels if she wants to stay relevant.
Pro Tip 3/3Achievement Context
Most appropriate when discussing past achievements and future potential. 
He’s been the leading salesperson for a year, but he shouldn't rest on his laurels.