It's a marathon, not a sprint.

cliché This task or activity requires endurance and persistent effort over a long period of time, so an intense, unsustainable amount of initial energy will not be successful. Look, we want a long-term marketing strategy that will build our brand over several years, so there's no point blowing our whole advertising budget on some crazy campaign that only lasts a month. It's a marathon, not a sprint. Any seasoned politician can tell you that, when it comes to elections, it's a marathon, not a sprint. If you burn out in the beginning, you'll make it much harder for yourself nearer the end, when it matters most.