Gratitude is actually something can enhance your performance in athletics and beyond. Gratitude can become a habit and can flow through you naturally after some time. Like riding a bike, driving a car, walking, or any other act that becomes unconscious through repetition, gratitude can become a default state which emerges effortlessly.
The one fighter in mixed martial arts which really embodied the spirit of gratitude was Randy Couture. He'd have a perma-smile on his face because he really was extremely grateful for living a dream, finding his passion, and living out what he felt was his life purpose. He had a very enhanced level of gratitude for what he did for a living and that was one of the reasons why he was able to fight until 47, and actually had some of his greatest accomplishments after the age of 40, on route to becoming of the greatest fighters in UFC and MMA history.
The following quote is from the book The Best Tennis Of Your Life: 50 Mental Strategies For Fearless Performance, but can be applied to any sport and any discipline of life: