This!

I've always had a similar mental block telling me that I can't possibly run. I'd wanted to start Couch to 5k for at least a couple of years, had the program all printed out and ready to go, but there was always a reason why not: too fat, too slow, too unfit, not physically suited to running...

Then tonight when I was looking up C25K online yet again, I read that quote and something clicked. I put on some gym clothes and went out in the street and did my first C25K session, just like that!

Of course I was slow and I sucked at the jogging parts, but you know what? Not only did I survive the 20 minutes of alternate walking/jogging...I absolutely loved it! Now I'm buzzing and can't wait to go again.

If I did it, you can do it too! Don't think about it, just do it! :D

I think its exactly like you said.. its a mental block. dig deeper. Why are you avoiding this? You can run, you know you can. But why wont you allow yourself to accomplish this task?