I'm sick?
Yes, practice at home. You don't want to get anyone else sick. Just do what you can.
If you have a fever, just rest.
I'm injured?
Yes. Talk with your teacher in person, they'll be able to give you specific instruction on what to do and how to proceed. Practice is effort toward steadiness of mind. It really isn't about the asanas. Your asana practice might be a bit different when you are working with an injury. That is really totally ok.
I'm menstruating?
No. Rest during your first three days of menstruation.
I'm pregnant?
Maybe. Talk with your teacher in person.
I'm feeling sad/tired/scared/angry/upset/happy/etc.?
Yes. See "effort toward steadiness of mind".
I'm sore?
Yes. Let your teacher know.
I'm unsure of what to do/forgot what to do?
Yes. Just show up and try to remember. If nothing comes to you, your teacher will. However, nothing will happen if you don't show up.
I'm a beginner?
Yes. Just show up. Your teacher will show you what to do.
It is a moon day?
I missed days and dread what will happen?
Yes. Just show up and see what happens. No fear.
I don't like it/am not comfortable?
Yes. It is okay to feel confused, emotional, uncomfortable, etc. If you trust your teacher and have faith in the practice, it will pass. If you don't trust your teacher and don't have faith in the practice, find a new teacher and maybe a new practice.
I'm hungover/constipated/hungry/ate something right before?
Yes. Just show up and see what happens. That is how we learn.
Right, so yoga is the cessation of the thinking mind so that one can see the true nature of the self. Practice is effort toward steadiness of mind. It all starts to come together through consistent, dedicated, uninterrupted practice, done over a LONG period of time. So really, you are practicing 24/7. The asana bit, the ritual where you show up to work on the
tristhana happens "every day". Monday, Tuesday, Wednesday, Thursday, Friday and then rest on either Saturday or Sunday and moon days. This system works pretty well because some days you'll be like "Yay yoga!" and it will be easy to show up and other days you'll be like "Snooze!" If you have designated rest days, then when the mind starts setting up obstacles, you can say "that's cool, we'll rest on Saturday, today I'm going to practice no matter what!" And then when you hit snooze anyway, show up the next day for sure. And then when it happens again and again and you think you can't go back, let the feelings go. Turn that passion toward getting back tomorrow.
It is sort of like maintaining a long-term relationship...it can't only be about the physical. Looks fade. Get interested in what can't really be seen, the inside stuff. Try to figure out this steady mind thing. Let go of the asanas.
Of course, you can't learn yoga from a website. Ask your teacher about this stuff. Do what they say. See what happens.