Anhidrosis is the absence of sweating, and these five factors are most likely to blame.
Not Working Hard
When you work out hard, your heart rate rises, causing you to sweat and burn calories. You're probably not working hard, and your heart rate isn't rising.
Dehydration
Dehydration is a common cause of not sweating during a workout, particularly in the winter.
Your Environment
Most people sweat more in hot, humid weather, so if your gym has air conditioners, chances are they are keeping you cool.
You Are On Medication
Medication, in addition to diuretics, can cause dehydration, which is why you do not sweat during a workout.
You Are Doing Same Exercise
When you do the same activity every day, your body adapts and stops raising your heart rate, which is why you don't sweat.
Bottom Line
Best way to sweat during a workout is to wear two sets of clothes and engage in activities that raise your heart rate, such as running or swimming.