I agree with having others influence others. You are the 5 people u mix with. If u mix with negative people from time to time, eventually u'll be one of them. That's why as an entrepreneur, it is very crucial to mix with like-minded people.
From what I learn as an experience to deal with low self-esteem, or low self confident person. If it is in a group scene where there are tasks involve. You can actually give the person a task, and when he/she does it well, praise her in front of everyone about how well she has done it. This is one way to boost someone's self-esteem and confidence. Works for someone with anxiety as well.
It also starts from within !!. Others can be whatever they want, if you are strong enough to influence yourself it's good enough. If you can influence other that's awesome.
yeps yeaps. :)