We often say to ourselves that "I will take the training tomorrow instead" and we shoot at the unpleasant instead of doing it now. 

This is something that in psychology is called procrastination. Procrastination is something almost everyone more or less "suffers from" because we humans have a tendency to compromise on long-term goals in exchange for short-term rewards.     

                                                                                                                                                              The bottom line is that most people need help, which is also a reason why professions such as coaches, personal trainers are growing rapidly. A good and simple tip, if you tend to procrastinate, is to break down the long-term goal into much shorter and more concrete parts, which are close in time. The smaller the step - the more likely you are to do it. Baby-steps!

Say your goal is to run the mile for 50 minutes in a year. A first step, to get started with running, could be to run 2 times a week. Once a weekday, and once a weekend. And then remember to reward yourself when you did. Each time. Good luck!