How often do you definitely say “I can’t”?
Not in a, “Sorry, I can’t make it tonight” kind of way, but a “I can’t do a pull-up” or even “there’s no way I can finish that”.
Do you even realize you are doing it?
Do you realize that you are putting false limitations upon yourself?
The questions shouldn't even be “what if I can?”.
The questions should be:
“How can I make it happen?”
“What do I need to do to make it happen?”
Because, here’s the thing, you can do a pull-up! You can run a sub 7 minute mile! All it takes is commitment and work. You are holding yourself back so that instead of being disappointed you are allowing yourself to be less than you can be.
There are no limitations to what we can achieve. Look around, you will see 80+ year olds running marathons, 70+ doing pull-ups (and muscle-Ups), individuals with Multiple Sclerosis pushing back barriers, and soldiers (and others) doing incredible things as amputees.
The word can’t does not exist to these people, and it shouldn’t to you. There is nothing to gain from saying I can’t and everything to gain from trying and failing. Fail early, fail often, fail as much as you possibly can. Because failing means you are trying. Failing means you will one day fail no more.
Remember this, Nothing that you can currently do well, could you do the first time that you tried it.
There is no benefit to ‘can’t’. There is no upside. So the next time you think you can’t, stand up and prove to yourself that you can.