when will it get easier?

i've been doing yoga on a regularly for a couple months and i keep thinking that at some point it will get easier. obviously i'm wrong. tonight was another ass kicking by Betsy my yoga teacher. don't get me wrong i love the class but it was rough and towards the middle i really didn't think i'd make it through. seriously my legs were shaking my arms were shaking...it was rough. i am really happy i made it through class b/c i was seriously considering leaving.