Staying humble is one of the most difficult things to do. Whether it's doing good on a test in school, landing a job interview, or succeeding in sports, our first instinct is to praise ourselves. In most scenarios, it is very acceptable to be proud of yourself.
For example, if you hit a homerun in baseball, you will reflect on all of the training and hard work you put in. Because you took the time, you had the ability to hit your homerun; and that is great. You should always be proud of yourself and have a great self-esteem, but should you gloat to all of your teammates and friends about your accomplishment? Probably not.