Having a coach is a luxury. For us software developers the closest thing we get to coaching is a code review by a more experienced developer. That is certainly

Having a coach is a luxury. For us software developers the closest thing we get to coaching is a code review by a more experienced developer. That is certainly valuable but rather hard to come by consistently if you are past certain level. So what to do without a coach? Find something that will direct your practice. For this reading quality code is indispensable as it shows you the range of possibilities of what you can do with certain technology. Considering your example of sports: past certain level it is essential to meticulously study video footage of yourself and your opponents in action as it provides insight into your weaknesses and your opponents' tricks which you can then adopt or learn to counter. Also when someone comes with spectacular advancement in technique (think Fosbury flop) it is quickly analyzed and adopted by others. So watching others is sometimes very useful.