老骥伏枥，志在千里
lǎo​jì​fú​lì​zhì​zài​qiān​lǐ

old people still have high aspirations

老骥伏枥，志在千里 老驥伏櫪，志在千里 lǎo​jì​fú​lì​zhì​zài​qiān​lǐ
old people still have high aspirations
Literally "an old horse in the stable still dreams of running a thousand miles"; used to describe an older person who still possesses great ambition and energy.