Give the correct form of the words: John Cena used to be in his _____________ in WWE but since his dislocation, he had to leave for operation and it would take him a long time to make a full recovery. (DAY)

John Cena used to be in his heyday in WWE but since his dislocation, he had to leave for operation and it would take him a long time to make a full recovery. 

Dịch: John Cena từng ở thời kỳ hoàng kim ở WWE nhưng kể từ khi bị trật khớp, anh phải nghỉ để phẫu thuật và sẽ mất nhiều thời gian để hồi phục hoàn toàn.