When you come to Yoga, please feel free to feel tired, even exhausted, even achy. Yoga is there to sort you out.
BUT, if you have your period, PLEASE let the teacher know. Some postures are better for you, some are not advisable (inverted postures, strong twists).
If you have a bad back, bad foot, a stiff neck, never mind. Do come and ask the teacher to find for you a nice relaxing pose. A lot of discomforts can be relieved through relaxation.
Please, do speak to the teacher, either before or after the class. It’s very pleasant to know how you feel and if the class has been beneficial.
If you really need special attention, then please ask for a one-to-one session.