Keanu Reeves kept it coming in The Matrix movies, but the role of Neo wasn't initially offered to the actor. Will Smith turned down the role [1] saying, "I would have absolutely messed up The Matrix. At that point I wasn't smart enough as an actor to let the movie be — whereas Keanu was." It takes a mix of maturity, self-awareness, and instinct to know when a project is more than you can handle, and it's an important lesson for our working lives.

Will's career was obviously unaffected by his decision to reject the role; in fact, if he went forward against his instincts, perhaps he wouldn't be flashing that smile as the biggest-earning actor [2] in Hollywood. We should always be up for new challenges that add to our career development and take calculated risks, but know when it's better to back away from a project that's over your head or if you aren't nearly qualified for a job that is offered to you. Be confident about your abilities, but be realistic and let your instincts guide you.

Source [3]