The Frustration of MTTs

I've played in several MTT's in the last couple of days and I haven't managed to do well in any of them. On some I've gone out on horrendous beats (which I feel like I'm taking more than my share of at the moment) and in some it's been on poor decisions where I end up getting my money in with the worst hand. I don't know what it is, I know some people are really successful at these things, I just can't seem to figure out what it is that I need to do. I can't figure out where I'm going wrong. I read Harrington's books, and I felt like I was starting to make a breakthrough and play better, but now I think I'm regressing. I just don't know where I'm going wrong. It really, really frustrates me when there's something like this that I know there is a way to beat and I can't seem to figure out how to do it. Couple this with the fact that I haven't had a decent winning $1/$2 session in about a week and I'm really frustrated with poker at the moment. It's these moments when I start to have the self-doubt and wonder if I'm really good enough at this game. I know I'm good, I know I have the potential to be good, but I just start to wonder if I can really make myself into the player that I want to be, and make myself into someone who can do this for a living. I dunno, I guess I just need to keep grinding and working on my game. The breakthrough is bound to come sooner or later.

Current Bankroll:
about $760