我愿用毕生的展颜只为换你回眸一笑
[wŏ yuàn yòng bì shēng de zhăn yán zhĭ wéi huàn nĭ huí móu yī xiào]
Translated as 'I am willing to smile all my life just to get a glance of your return smile', this implies a deep devotion or affection where one party wishes their efforts, represented here by smiling lifelong, could bring happiness to their loved one (a glance of smile). It indicates unreserved adoration for another person.