Be confident in your ability to compete. You don’t have to win every time. You won’t win every time. But you can always compete…Try your hardest, have a good attitude whether you win or lose, and make sure you learn from your experiences.
If you don’t like losing, keep practicing. Keep competing. Be a student of the game. What worked well before and what didn’t work? How can you implement what worked and reduce what didn’t to get more consistent results? Become an expert in whatever it is you’re trying to do. With competence comes confidence.