Many people think that it is IQ, good looks and physical health. Angela Lee Duckworth don’t think so. She thinks it is grit. Grit is passion and perseverance for very long-term goals. Grit is having stamina. In fact, according to her research, grit is usually unrelated or even inversely related to measures of talent.
Learning English used the same way. You don’t have a high IQ. You need learn hard day by day. Never give up when you have difficulty to learning English.