persist
To keep trying and not give up, even when hard.
To persist means to keep going even when something is difficult, boring, or discouraging. When you persist at a hard math problem, you don't give up after the first try, or even the fifth. You keep working at it, trying different approaches until you figure it out.
Persistence matters because most worthwhile things require it. Learning to play an instrument means persisting through months of awkward sounds before making beautiful music. Training for a sport means persisting through tired muscles and failed attempts. Building a friendship means persisting even after disagreements or misunderstandings.
When scientists persist in their research despite failed experiments, they eventually make discoveries. When inventors persist after repeated failures, they create things that change the world. Thomas Edison famously persisted through thousands of unsuccessful attempts before inventing a practical light bulb.
People sometimes confuse persistence with stubbornness, but they're different. Stubborn people refuse to change their minds or methods. Persistent people keep working toward a goal but stay flexible about how to reach it. You might persist in learning to ride a bike, but you'd adjust your approach after each tumble, trying different techniques until you find one that works.