“Believe you can and you’re halfway there.”
― Theodore Roosevelt
“I can’t” is probably the most limiting belief a person can ever hold. “I can’t” is automatically a true statement if you believe it.
Of course, more often than not, “I can’t” really means “I give up.” Maybe I tried something that didn’t work, or I tried a bunch of things that didn’t work. Maybe I failed last time. Maybe I’m afraid to screw things up again. Maybe everyone says it’s impossible.
You need to ask yourself, “How bad do I want it?” If it isn’t important to you, move on and don’t worry about what anyone thinks. On the other hand, if it is important to you, then don’t give up without exhausting all your resources, looking at every angle, and testing all possibilities.