I am far from an expert, so take this with a grain of salt.
If you train less than 8 hrs a week, I wouldn't sweat it too much. Just try to vary your rides in intensity and duration. Try not to get bored, as burning out will be the worst thing for your training. In the off season your workouts will tend to be longer duration, lower intensity. As your target season approaches, transition to shorter, more intense workouts (intervals). Make exceptions, ride with friends, listen to your body. Stretch often (after riding, I wouldn't bother stretching before), and eat well (eat enough!).
If you start training 8-12 hrs a week, just make sure you have 1-2 "recovery rides" (~1hr very low intensity/no intensity) per week mixed in with your training. Do more stretching, massage, etc.
If you start training more than 12 hrs a week, you need to spend some time reading a good book (e.g. The Cyclist's Training Bible) or working with a coach.
Most of all remember to appreciate the feeling every time you get on the bike - it's why we ride!