To be complacent means to feel so satisfied with how things are going that you stop trying as hard or paying attention to potential problems. It's a kind of dangerous contentment where success makes you careless.

Imagine a soccer team that wins their first five games easily. If they become complacent, they might skip practice or stop studying their opponents, assuming victories will keep coming automatically. Then a well-prepared underdog team surprises and defeats them.

Complacency sneaks up on people who are doing well. A student earning straight A's might become complacent and stop studying carefully, then struggle when the material gets harder. A business that dominates its market might become complacent and fail to notice a creative new competitor.

The word suggests more than simple laziness. A complacent person isn't necessarily sitting around doing nothing: they're working, but without the alertness, effort, or hunger that got them to success in the first place. They've started to coast and assume things will work out without their full attention and energy.

The opposite of complacency is vigilance: staying sharp, curious, and hardworking even when things are going well. Champions in any field know that complacency is their enemy. The moment you decide you're good enough and stop pushing yourself to improve is often the moment you start falling behind.