How do I stop being slow and making mistakes on the assembly line?

Being slow and making mistakes feels like proof you are not cut out for this, but it is almost always just proof that you are new to it. Every fast, accurate person on that line was once exactly where you are. Speed is the last thing to arrive, not the first. And chasing speed is what causes the errors. When you rush to keep up, you skip the small checks that keep the work right, and then fixing mistakes costs you more time than you saved. So flip the order. Aim to be correct first and steady second. Accuracy becomes a habit, and speed grows on top of a habit that already works. Start tomorrow with one rule: do each step right, at whatever pace that takes, and quietly check your work before moving on. Track your errors for a week. As they drop, your speed will climb on its own, because you will stop losing time to redoing things. Slow and correct beats fast and wrong every day.