I'm going to let you in on something that's quit upsetting to some. It's something many people may disagree with but it's a cold hard fact.
This is not a made up thing, it's psychology. Whatever your basic personality is, you are stuck with it and nothing will change that. In the short term, changes may be noticed but when people are left to behave in their own ways, they always resort to their old personalities. If they are lazy, they remain lazy. If they are charismatic, they will always have charisma and this goes for all personality traits that have been chiseled since childhood.
This seems very self defeating when you read this, but there is hope.
How to change someone
There is only one way to change someone, and that is to start by changing yourself. Remember, you can't change your personality but you can change your thinking, skills and habits, this is key! By beginning to change yourself for the better you become a role model to others, and motivation is what gets people to change not nagging or wishing.
Everybody has an "Ideal self" they want to achieve in their minds and they will do anything to reach that, but they must see it's possible, this is where you must show them. Become your "ideal self" through learning new skills and make the necessary changes to become "Fantastic" you notice others around you asking you for advice, it's up to them to follow your advice. You become a mentor and no longer a nag.
People have developed into who they are from many thousands of days of being exposed to different things that life has brought them. This is why you are unable to change people. Accept who they are, and become the best you can be...This is how to change people.