When I was a child, I used to ask all sorts of questions. My favorite words were "Why and Why Not?" I think my parent were sometimes amused at my curiosity and at other times they wanted to just glue my mouth shut with duct tape.
We live in a world where people more often are concerned with saying NO or YOU CAN'T because it's easier than saying YES or YOU CAN. Saying "yes" or "I can/You can/We can" is hard because it requires you sometimes learn something new, change, or in general it just requires some effort.
The beautiful thing is WE (you and I) choose what we can and cannot achieve. We all have the power to do what we want to do. If you want it bad enough, you'll put lots of YES/I CAN and effort into it. Likewise, it will mean more when you do achieve it.
I think we live in a world tainted by negativity and disbelief. But I can see why...our media and ideas of what is right, wrong, successful, unsuccessful are published through the eyes of others.
Don't settle for mediocre role models, friends, colleague, and leaders. If someone tells you that you CAN'T....just ask yourself ...
WHY? WHY NOT?
And get on with it.