We have all, at one time or another, had those uninspiring training sessions. Those sessions where you feel stiff and achy, the weights all feel heavier than normal, and you don't move very fluidly. Some days you just don't have it. You may even have been training regularly, making good progress, and are following your training schedule perfectly. On that particular day, though, you don't feel good physically and mentally your are unmotivated. One of two things usually happens. You either don't even bother training or you push yourself through the session anyway (think Biggest Loser).
Skipping that workout may be ok, occasionally, for some, but that can be a slippery slope for others who easily lose focus. They may be at risk of falling out of the habit entirely for a long period of time (weeks or months).
For the strong-willed who push themselves through the workout, I can assure them that they are not getting in a productive workout. They are probably not setting any personal bests, and are probably walking out of the gym feeling worse than when they came in the gym.
Over the years of training myself, I have periodically tried to stay on a planned, regular training program. Everything is planned out. The specific exercise, the exact weight, reps, sets, rest, etc. are all set out for me. I end up doing it for a while and realize that it doesn't work out so precisely. Something is missing. The results are less than spectacular. What I have come to realize is, that I cannot predict the future. How am I supposed to know how my body and mind are feeling in two or four weeks? I don't. I am only controlling a few variables (exercise), but the body is so much more sophisticated than that. How long do I need to give myself to fully recover and be ready to be challenged again? Your guess is as good as mine.
Knowing When To Go
Knowing when to go is the answer. But, it is also the question- when do you go? Only you know that. We cannot separate the body from the mind. They are intricately connected in a psychosomatic (or mind-body) interaction, which can be extremely complicated.
I have found that you need to test your psychosomatic training readiness on a regular basis to see when you are ready to go. What does this mean? It means that you need to plan on training regularly (such as Monday, Wednesday, Friday) and start off with your warm-up, mobility, and an easy version of the exercise(s) you are planning for that day. Only after doing all that (maybe 10-20 minutes) will you have an idea how hard you can go that day. You can rate your readiness on a scale of 1-10. If you are feeling like Popeye on a case of spinach, then it is a '10'. If you are feeling like the new parents to colicky triplets without a Starbucks in sight, then it is closer to a '1' and you are probably not ready for a hard workout. I equate it to 'testing out' a physical injury (i.e. a sore back) to see how it feels after you complete your warm-up.
If you rate your psychosomatic training readiness fairly high, then you are ready to train hard. If you rating is on the low side, then maybe that day should be an 'easy' day to allow for continued recovery. That way you are assuring yourself that you will be more ready during the next workout to train hard. However, you can still do light exercise, foam rolling, flexibility, mobility, and technique work on your 'easy' day. Again, you want to allow yourself to continue to recover.
By 'listening' to your body by rating your psychosomatic training readiness you will know when and how hard to train your body. You can also maintain a regular training schedule, which is important to develop good, long-term exercise training habits. Use this 'training tool' to assure that you always have a good training session and see better long-term results.