Whether you train with a coach, on your own, or use a pre-written program, you are going to need to adjust your training program at times. General fatigue, lack of time, and life in general will always play a role in preventing training and missing training days. So what do you do? The good news is a few days missed will not affect training at all. It will throw you off a little both physically and mentally but there are ways to adjust.
To do well as an endurance athlete, season goals need to be set early to provide the motivation needed to train hard. It takes a long time to build endurance and reach peak fitness levels, so the sooner you start with setting goals, the better. Your goals can be loose, precise, large or small, just as long as they create the desire to work hard. Most importantly, season goals should be set around something you love to do.