Why do some people lose their motivation to work hard?

I think one main reason people lose motivation is when they don't see progress in their work. Like when I was learning video editing, at first I spent hours just to make a two-minute clip, and the result wasn't great. It was frustrating, and I almost gave up. But once I started noticing small improvements-like smoother transitions or better pacing-it kept me going. In Shanghai especially, where everything moves fast, people expect quick results. If they don't see any payoff after putting in effort, they just lose steam. That's why breaking big goals into smaller milestones helps-it gives you those little wins along the way.