Start with a powerful quote or a vivid image. For example, "A river cuts through rock, not because of its power, but because of its persistence".
Depending on your goal, you can approach this in a few ways: a (your own story), a Definition Essay (explaining the concept), or an Argumentative Essay (arguing why it’s the most important trait).
Argue that talent is often overrated. Many people with natural ability fail because they lack the "grit" to keep going when things aren't easy.