那个太过于天真的大孩子那颗骄傲而不知疲惫的心
[nèi gè tài guò yú tiān zhēn de dà hái zi nèi kē jiāo ào ér bù zhī pí bèi de xīn]
Refers to 'that overly innocent older child who has a proud heart that never tires'. This portrays someone with childish innocence yet carries a lot of pride and energy despite age.