In an interview with UFC featherweight Dustin Poirier, he notes that enjoyment for what you do is necessary to succeed:
This is a job, where it takes so much out of you and it takes such dedication, that if you don't enjoy it, you can't do it. You won't be successful.
It's kind of reminiscent of a quote by the BJJ and MMA legend Rickson Gracie, who noted passion is the backbone of succeeding, because it will be the thing that allows you to overcoming adversity which crops up along the journey:
"The journey has to be based on passion. Put yourself in something you love to do. If you love what you do you're able to dedicate yourself, overcome obstacles."