I Can'tI hear people say "I can't" quite often. My kids Nigel and Max use to say it all the time. I'm sure I've said it also. These two words can do more than anything else to prevent you from learning Excel.
Along with "I can't" you'll often hear people say "I'm not good at...." In the words of Henry Ford, "If you think you can, you're right. If you think you can't you're right." He also said, "If I'd ask people what they wanted they'd say ‘Faster horses'". (This is not relevant, just one of my favorite quotes)
I would tell my kids, "Don't say ‘I can't!", say ‘I can't yet!'"
I also hear people say, "I'm not technical", "I'm not good with com-puters", "Only kids can do it." Each of these statements may be true, but they're only a temporary state. Everyone that learned Excel was once in this state.
"You can't teach an old dog new tricks." This may be true for dogs but not for people.