great responses..
a couple things though they will be much less brilliant than Edwin's replies
Regarding working on the inner critic...
In life, there are things that just are. Like if you fall down, you might say, "OUCH!" and then get up or "that was stupid" and then get up but the thing is you get up. So you could say to yourself, "hey, maybe next time I fall I'll just get up and not say anything". The get up step just IS. You do it. Adjust the way you look at your meditation practice to be sort of the same - I just practice, my practice IS, it's what I do. How it goes also IS, the thoughts are, the itchy nose IS, etc..
Regarding the reaction to or observing thought..
mantra, mantra, mantra, mantra, mantra, mantra, I wouldn't mind having a sandwich right now, that salad last night was amazing.. ah, thoughts... mantra, mantra, mantra, mantra.
If you just notice the thoughts and think "ah thoughts" or something like that, take a look at what you are thinking (or not) then continue without making it wrong or whatever, pretty fine I think. The "catch" is to not get caught up in the story of the thoughts, where 20 minutes later you are so deep in the thoughts you could have written a chapter in a book.
But, things happen - that's why it's called a practice.. you don't just lift weights once and you're fitness champion of the planet... there's demons to face and exorcise, a lifetime of obsessive thought habits to work out and a multitude of other things. All in a days work so to speak.