There are times when something is genuinely out of reach, when practically-speaking we are not likely to pull something off. But those times are fewer than we think. You have walled off some of your juicy potential with small-minded games, under the mistaken belief that what you really want is not possible. It probably is possible, but you'll have some excavation to do to get to the level where you have unconsciously denied yourself permission to fully live your dream.
I'm not going to the moon under my own power anytime soon and a one-legged war amputee is not going to best Usain Bolt in a sprint (the word "bolt" is literally his last name). But those are extreme examples that don't define the rules of what is possible here on Earth. Grow or maintain and eventually shrink in the face of real opportunities to shine: those are the two mindsets.
I make up a lot about the headspace someone is in simply by listening to their language. Is it constructive or nonconstructive? Empowering or defeatist? There are a few common lexical forms people use which betray attitudes that are somewhat less constructive and self-defeating.
"I can't!" doesn't necessarily mean someone is not capable.
When my children were young and we were teaching them to climb, they'd often get stuck part way up. They rarely got stuck from a lack of physical strength or skill, but from the creative failure to put the puzzle pieces together. At this point they would normally make the somewhat whiny complaint, "I can't...[overcome the challenge]" This is self-limiting disability language: they were both able to knit the moves together, they just hadn't yet. It's just a capacity challenge that requires a bit of patient problem solving and some experimentation.
"I can't!" sometimes means "I don't want to".
I also hear that same rebuffal when people are declining a request, offer or invitation. "Hey are you free to go out for dinner on Saturday?" "I can't...[insert plausible sounding excuse here]." People use this form when they don't really want to do something, so instead of saying, "no, thank you", they feel compelled to save the feelings of the other person with well-meaning, but nevertheless false courtesy. I'd rather you just say no, so that I understand your preferences and maybe make an offer more to your liking. And if it's just me you don't like, the truth saves a lot of time and aggravation. That message can be delivered with real courtesy.
Each of us has decided how willing we are to win.
Another set of phrases weaken the real intention and commitment to follow-through on something ostensibly important. Whenever I hear someone say, "I have to workout", "I want to work out", "I'm going to workout" or "I will workout", I assume very few workouts will occur: I'm pretty sure they are preordaining their failure. Those phrases lack real commitment. When I make constructive commitments to follow through on something, it's not because I have to do anything; it's because I genuinely intend to complete on it. "I am working out" is ability language.
In order to live your dream life, you have to be willing to stretch your notion of what's possible and experiment with different ways to make it work. Some things will work beyond your imagination; other trials will fail miserably. Are you willing to try something new on the off chance it might work and prove your self-judgements wrong. And if you are not willing to step forward into a bolder vision of yourself and your potential, are you at least willing to be willing?
Growth means grasping what was previously out of reach.