Face it, tennis is a hard sport and it’s a mental sport.

Tennis is going to test your character as a person, but the great thing about that is, you will be able a build a stronger one while playing the sport. The first step in this “fighting spirit development” is to learn how to deal with failure and setbacks, by mentally recovering as soon as you can. You can do this by not taking it personally.
One match doesn’t have to define your career, now does it?
See, by focusing on our failures most of the time, we keep that dark memory etched into our subconscious minds all the time, and this reliving of it again and again is really mental suicide for many junior players, because they are killing their own self-image over and over when you do re-live it.
Discovering your own fighting spirit is actually fighting for your own self-mastery, meaning you will do anything that you can to stay away from thoughts that will weaken your mental game. Do it for a day first, then go for a week, after a month, you will be feeling stronger. The secret that few tennis players get is that, they really are the ones holding themselves back. Try to be aware of your thoughts daily and ask yourself this key question.
“How will thinking this way, affect my energy?”
I’m talking Law of Substitution here. Anytime a negative or failure thought comes into your mind, cast it out, then replace it with a more empowering one!
The next step is to start playing every point with a do or die attitude in practice, players think they can turn this mindset on and off, but they can’t. Practices makes perfect, so start in practice, you can then let it carry over into your match play. This is how the Champions mentally train daily on and off the court.
That’s what separate them, from the rest of the players on tour, they want to be the best and they know a fighting spirit comes from playing at a certain high level all the time and that this is the only way to get there. Finding your inner fighting spirit, is a journey.