Foot Health
This is a good article on keeping your feel in tone and strong for balance and safety. The article suggests it's even the secret to a long life but aren't so many things according to the experts. But we all have to walk so having your feet in tip top shape makes that happen.
Chemicals in Water Threshold Lowered for Safety
Life of Regret - how to avoid it.
This is great advice and what it ties into is your self image and what you expect of yourself. If you don't match up to what you dreamed of doing and being or at least working toward it then yes you might feel failure and regret. Relative to your dreams of a career in tennis many of us have had to make compromises. In my own case a matter of injuries, finances, and reality of my existing options led me to choose teaching tennis as a life career. Of course we all would love to play competitively for a living but I saw teaching as a way to stay with tennis throughout my life. The reality is that a majority, a very big majority of those who tried to make a living playing end up teaching anyway. Of course it does give you a leg up in terms of credentials to at least have played professionally even if not successfully enough to stay with it. Think of this when you plan your future on the court and consider that everything you do is eventually leading you toward sharing your skills and what you have learned with others. In the meantime enjoy every day on the court whether it's as a player or teacher.