Not everyone can change you, motivate you to become a better person, make you right your imperfections. Mostly the person who can is the one who doesn’t do that by telling all that out loud to you but by being so nice and perfect himself/herself which leads you to feel deeply impressed and fully convinced that yes, yes these are the characteristics I need to adopt too, these are the ways I should follow too. This person is the one who has no intention in particular to do so but still makes us realize the flaws and weaknesses in our personalities and to be honest twenties really is the time of and for transformation because you yourself strive to become perfect or somewhat perfect therefore you welcome any suggestions and advises (that are subtle otherwise we lose our minds too :p) otherwise in teenage you mostly Over or UNDER estimate yourself.
I have started noticing that a person who is your age fellow and is better in any way can be the best influencer as you can relate to him/her and without being lame and you can clearly see that if he/she can do it at my age, I can too. That is the reason why ‘AGE’ is the most used demographic element to make a sample group for any study/research because physical and emotional characteristics/hormones are highly linked to and interdependent on age and people find it convenient to relate themselves with the people of same age than same status, race, nationality, religion even gender which is why all teens are referred as energetic, aggressive, sensitive etc and all old people are considered weak, experienced, emotional and sometimes nagging etc.
So look for a better person of YOUR age to make him/her your councelor/influencer rather than someone older or younger! Because we all know that in the end we never learn or want to learn from the experiences of our elders. :p