tā / yì / kāi / shǐ / jué / de / zǎo / qǐ / hěn / nán / hòu / lái / xí / guàn / chéng / zì / rán / le

他一开始觉得早起很难，后来习惯成自然了。

At first he found it hard to get up early, but eventually it became second nature.