You can actually train yourself for a more positive attitude with what neuroscientists call self directed neuroplasticity. Simply put its training of the mind and the emotions thru mental exercises like meditation and affirmations. Ive done it to get rid of mental diseases like social anxiety, depression, addictions. You can literally rewire your brain for more confidence, releasing old negative patterns and just an all around more positive attitude. Would you rather have neurotransmitters associated with fear and/or self doubt or do you want your mind to be focused and confident that you can handle the courses. Obviously you NEED to practice but if your mind is wired for more positive ways of thinking it will release more motivating neurochemicals that will energize you instead of slow you down and can even make you feel more tired.
There is a whole realm of training the mind in this area that goes back 1000s of years that holy men and warriors have been using to keep their minds sharp and tuned up like a high performance machine. You could always leave it up to the randomness of what your parents and society taught you....
Its just like lifting weights but for the brain as the brain is a muscle and a super computer in one. You might as well be the programmer of the computer by training it for better ways of thinking, emoting, perception and behavior. In 50 years time this will be standard for all professional and serious athletes as well as other people who want the highest performance of themselves. Training the mind properly is a powerful addition to training the body.