Recently in the news I've been hearing about NBA players having panic attacks and depression issues. Playing tennis is no different if anything since it is not a team sport except Davis and Fed Cup Mental Fitness is of highest priority. If I let emotions take over and beat up on myself over errors I'm making. I will definitely lose focus and not have fun or success. You just have to have positive coping skills to get into a better frame of mind. Be mindful. and try to stay in the moment and not think about the past or future while competing. I admit mental and physical fitness are linked. It's important to have a balance between both in life.
Which league are you a member of?