Asana means "comfortable seat". It does not mean "cirque du soleil performer". Don't be discouraged or intimidated with crazy hard poses you see around Instagram. Yoga Asana is about getting the body ready to sit comfortably in meditation. You want to train your body to be a "friend and an accomplice" as Iyengar says in Light on Life. Asana calms and strengthens the nervous system while yogic breathing or pranayama calms and strengthens the mind.
Each pose that you advance to, you are to find comfort in it. Comfort means that you can steady your gaze, take full complete breaths without strain, and find balance between the struggle and the ease.
Yoga is not about joining the circus. It's not about throwing yourself into a pose because your neighbor in class did it. Challenging your body to go farther as your body says to, not your ego, can be right for some people. Others will never stand on their heads and that is fine too. Remember, it's not about being a carni. It's about finding comfort in the uncomfortable.