You have to be a little naive at the start of your journey. Don't be realistic. Instead tell yourself "why not me?"

Believing your goals are possible, that's step #1.

Step #2: go to work.

Being "realistic" really means setting long term goals that others have decided for you have a high probability of success.

But if that probability is so high, maybe your goals aren't big enough.

This doesn't mean not to be brutally honest and realistic about your process for getting to those unrealistic long term goals.

Dream in the long term, but get extremely practical in the short term about your process for getting to the next checkpoint.

"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man."

- George Bernard Shaw

Not all goals end up being 100% possible, but to really push the envelope you have to find out where that line is. It's often way further than people realize.