Sure..., Unsure

Its a rare moment where we can be 100% sure of ourselves. We often question our abilities and if we don't we tend to be delusional. I seem to be the least sure of all people, but talking to people I find out that I'm more likely just the most honest.
Its funny that Im thinking of going into teaching and I just talked to a teacher last night that just quit teaching for good it seems. She is 26 and a lot like me. She still is wondering what she wants to be when she grows up although she has some good ideas. Anyhow, she told me she quit because she just couldn't be happy in an environment where she felt restricted from doing her best possible job trying to teach these kids something. I very much sympathized with her.
So do I do as I always do and let the negative things make me back away from my projected course or do I take them with a grain of salt and make the most of what I think could be a great career for me?
Or do I just go get a job fixing things no one else knows how to fix and make something like $50 an hour. Ha. We shall see...