You can discard the beliefs that aren't helpful anymore, and rework others so that they propel you toward your greatest dreams. In the short run, you can also choose beliefs that will leave you feeling better, happier, more peaceful.
There are some things none of us will ever do, like flying by flapping our arms. These truly do belong to the "I can't" realm. But what about those things that we declare outside our capability simply because we declare that we can't?