Not having your period can be serious and should be discussed with a doctor. If you find that your symptoms interfere with simple daily tasks, like going to work, on a regular basis, then you should see your healthcare provider. {relatedarticles}And it's OK to work other muscle groups, like chest and arms, when you're menstruating if it's simply uncomfortable to work the lower body. When it comes to exercise and your period, it's best just to go with the flow.