Despite what you may think, exercise is perfectly possible during a pregnancy. If you were rigorous about a routine before you became pregnant, chances are you can still maintain that program to some degree throughout the entire time you're expecting. As long as you pay attention to what your body is telling you and avoid dangerous positions and activities that could cause problems, you should be able to remain active, even during your third trimester!
However, if the thought of running or jogging with a huge belly is enough to make you vow never to leave your couch again, there's another option that you might find more appealing: yoga. This ancient form of exercise has many benefits and is gentle enough not to put a strain on your body when you stick to poses that are safe for pregnancy. As an added bonus, your mental health can also improve during practice.
Yoga can calm your mind and your body, helping you relax and put to rest all of those worries you might be having about going into labor or making things just right for your baby. It's also a great way to tone your muscles and strengthen your reproductive organs and pelvis to ensure a smooth pregnancy and childbirth.
Consider signing up for a prenatal yoga class, which can help you meet other expectant mothers who are going through the same things you are while keeping your special needs in mind. You may even want to consider taking a regular yoga class, as long as you tell the instructor about your pregnancy and which trimester you're in (and skip any studio with a super hot room for now!). That way, you'll be instructed on which poses to forgo and how to alter certain moves to compensate for your growing belly.
Once you're in class, be sure to drink plenty of water and take breaks when you need to. If you feel any discomfort at all, stop what you're doing and ask your instructor about another way to do the pose. You may find that even after your baby is born, you're drawn to the physical and mental benefits of yoga and yearn to shift into downward dog to relax and decompress.