积土成山

jī tǔ chéng shān

Meaning: lit. build a mountain by piling dirt; success is the cumulation of lots of small actions

On August 27, Xi Jinping gave a speech in Beijing about the last five years' progress on the Belt and Road Initiative. He stressed that we should not view the BRI as simply an infrastructure plan, but rather as a high-level, global governance and development strategy aimed at bringing the world into one harmonious community. He used this chengyu to emphasize that all the seemingly disparate parts of the strategy will eventually bear fruit, like piling dirt eventually turns into a mountain.

Original: 要坚持稳中求进工作总基调， 贯彻新发展理念，集中力量、整合资源， 以基础设施等重大项目建设和产能合作为重点，解决好重大项目、 金融支撑、投资环境、风险管控、安全保障等关键问题， 形成更多可视性成果，积土成山、积水成渊， 推动这项工作不断走深走实。

Source:  http://www.xinhuanet.com/politics/leaders/2018-08/27/c_1123336562.htm