“When should I exercise?” lends itself to the easy answer, “whenever you feel like it and even when you don’t.” However, in my daily dealings with real people in real situations, it is never that simple.
Exercise isn’t always the best medicine and, depending on the specific situation, can actually be a source of dis-ease.
For that reason, I would like to share with you a few times when inactivity is the most sensible option. The following are not lame excuses for not working out, but rather valid physiological bases for exercising your right not to exercise. These are brief… if you need more, you know where to find me. 
Don’t Exercise… in the morning. If you have arthritis or back pain, be very cautious about am exercise, especially during the winter months. Your body is stationary and cool as you sleep, and it needs time to warm up before activity. No matter what, don’t begin with stretching or strength training. Cardio comes first.
Don’t Exercise… in the afternoon. If it is mid-day and you haven’t eaten yet, skip the workout. Your body is running on fumes… not fuel for burning fat or building muscle. Also, if you just had lunch, your body wants to pump blood to your stomach, not your muscles. Digest for an hour or two first.
Don’t Exercise… in the evening. If you tend to skip exercise or have a family waiting, don’t try to work out after work’s out. Instead, make sure your fitness regime is finished before your day gets started.
Don’t Exercise… on Sundays. In other words, always take at least one complete day of rest each week. Remember, exercise is only effective with sufficient rest, repair, and recovery.
Don’t Exercise… if you’ve exercised. If you ran yesterday, don’t run today. If you trained biceps today, don’t train them tomorrow. Always rest tomorrow whatever you work today. Lack of soreness doesn’t mean that your body isn’t finished repairing itself.
Don’t Exercise… when your are exercising… and you experience any of the following “throw in the towel” symptoms: nausea, dizziness, pain or tightness in chest, difficulty breathing, or blurred vision. If something doesn’t feel right, trust your feelings and stop.
Don’t Exercise… if you don’t exercise. If you have been sedentary for months or years (or ever), make sure you get a physical before you get physical. A doctor’s work up is always recommended before a trainer’s workout, especially if you have high blood pressure, high cholesterol, diabetes, family history of heart disease, or if you are a smoker. None of these necessarily indicate that you can’t exercise… just not yet.
Don’t Exercise… if you haven’t exercised recently. It seems like every day at Stand Firm Fitness, my fitness center in Connecticut, I see a client walk in who hasn’t been here for at least a couple of weeks. It comes with the territory. Unfortunately, inactivity undermines fitness very quickly. Use it or lose it, right? For every week you take off, take at least one workout at a lower intensity to re-progress.
Don’t Exercise… if you’re sick. At least do a check up from the neck up. If you have a sore throat or nasal congestion, a light workout might make you feel better. However, a chest cold or bronchial hack deserves rest and relaxation.
Don’t Exercise… if you’re injured, at least not with that specific body part. There is a difference between working through and around an injury. A qualified physical therapist can help you work through… a professional trainer can help you work around. Don’t go it alone.
Don’t Exercise… if you smoked. I can’t think of anything more blatantly dangerous than smoking before or after exercise. Carbon monoxide in cigarettes has an affinity to hemoglobin 240 times stronger than that of oxygen. In other words, your blood can’t transport oxygen too well when it is being used by toxins. Because exercise creates a physiological oxygen deficit (during exercise) and an oxygen debt (after exercise), it is insanely dangerous to do anything before exercise that can limit the oxygen carrying capacity of your blood. Smoking literally sucks the wind out of your sails… away from the muscles, brain, and heart.
Other than that… enjoy your workouts!!!