This is a very common question. My initial response is, "whatever time works best for you!" However, each time of day has its pluses and minuses. Research tells us that those that exercise in the morning are more consistent with their workouts. This is due to the reduced likelihood of interruptions or distractions interfering with your workout. The downside to morning workouts is your body temperature is at its lowest a just before you wake up so you may find yourself struggling to get started. From a physiological standpoint, the afternoon is probably the best time of day to exercise. In other words, your workout will be better... you'll be faster, stronger, etc. Afternoon workouts can be a great way to break up the day and recharge your battery. The downside is that those distractions and interruptions you can avoid with a.m. workouts always seem to appear just when you grab your gym bag. Evening workouts may help you "burn off" the stress and forget the problems of your day. Be aware, there is still a chance of missing your workout because of unplanned disruptions. However, be sure you don't workout to close to bedtime because you may find yourself struggling to fall asleep. To prevent this tossing and turning, try to give yourself a couple of hours to unwind after you exercise. So, experiment and find the best time of day for you to exercise!