Although being humble and staying grounded is a postive thing, and it is a sure thing that no one likes an extremely coky person. Yet having doubt about oneself will be wn interference. People will continue to doubt themselves and become self caution and will prevent them from attempting to get out of their confomt zone, which will restrain them from success.
During a class project in my sophomore year, me and a group of classmates had to persuade people to agree on our ideas, and we had a variety of choices on ways to persuade our classmates. yet I believe my group were the most confident in ourselves, which was the reason we won and persuaded the most. I believe the reason we were the most persuasive was because we had certainty in our choice which showed our confidence that led to a influence on everyone else.
When you aren't certain about something, you would probably never attempt in trying it. Unlike the terriost who were extremely certain they would achieve their goal on 9/11, when thry aimed their attack on the world Trade Center in New York City. If the terriost were certain they would cause a lot of damage to us Americans they certainly would have never attempted the attack.
Having certainty will aid you to achieve the strength you need to do something. In order to achieve what is needed, yiu have to be certain on the choices you make. When people make the choice of leaving their homeland, bound to go to a different country in search of a better life, it is for nessaciaty and they are certain they will find a better place to go, which is the only reason they took the risk in leaving.