Tā ānwèi zìjǐ: jìláizhī zé ān zhī, mànmàn shìyìng ba.
He reassured himself: since you're here, make the best of it — you'll adapt gradually.
Tips
usage
既来之 is always used as the first half of the proverb 既来之,则安之, meaning 'since you've come, make yourself at ease'. It counsels acceptance of one's situation.