Stamina is the physical or mental strength to keep going when an activity gets hard or takes a long time. If you have good stamina, you can run laps without getting exhausted quickly, or study for hours without your concentration fading.

Think of stamina as your body's or mind's staying power. A soccer player with strong stamina can sprint up and down the field in the final minutes of a game, while tired opponents are slowing down. A marathon runner needs tremendous stamina to cover 26 miles. Students need mental stamina to focus through a challenging exam or finish a long book report without their minds wandering.

You build stamina through practice and persistence. Runners increase their stamina by gradually running longer distances. Musicians develop the stamina to play difficult pieces by practicing regularly. Your brain builds stamina for math problems by working through them consistently, even when they're tough.

Stamina is what helps you keep going when things get demanding. Without it, you might give up halfway through. With it, you can push through challenges and finish what you started.