How do you know which character God wants you to have?

Have you also noticed this? Some humans stay the same their whole life. Some humans were already picked on in grade school and it continues through their entire life. It's as if this weakness is attached to them and others can smell it and this is why they always stay in this position. And on the other hand there are also humans which always belonged to the "cool guys" even in school and it stay this way their whole life. I ask myself can a person change its character and become totally different or is this impossible? Can somebody who has always been picked on change his entire nature and basically act like somebody else? I have heard that people which went to a boot camp came back and they were changed. They got a stronger will and became more like fighters. But a boot camp is also an extreme example. Can a person under normal circumstances change their nature or will it always be fake and the others will be able to spot it and to recognize that it's all just a mask and behind this mask there is the same weak person which has always existed.
I think that it's not possible for such a person to change and become totally different because becoming different would mean acting different and thinking in different terms. I think even if such a person tried to play the cool,sovereign person it wouldn't appear genuine. But what do you do if you're not satisfied with who you are? What do you do if you don't like yourself and wish you were a different person? Somebody who has a strong will, who finishes what he started who doesn't seem to radiate weakness? But these are things which you cannot simply change even if you want to. But the others notice this weakness and when they notice it then they either treat you with less respect or they try to abuse you. But I really don't think you can get rid of this weakness because it's in everything. In the way you talk, the way you look, simply in everything. I think you cannot hide it at all.
But I really don't like myself because I want to be different but I don't even have the guts and the strength to be who I would like to be. This is totally frustrating and it angers me. If I could at least be who I want to be.
I don't want to be the nice guy anymore because being too nice is a weakness. Others spot it and they lose respect. You can be a nice guy but only to the people where you know that they will not abuse it. If you're nice towards the wrong people it'll not be beneficial for you.
How do I know wether I'm the way I should be or not? But if I don't even like myself then I don't think God wants me to be this way.
Sometimes I adore people which are rather simple. They simply have a thicker skin and also don't worry about so many things. They aren't so sensitive and all that. My father once told me that you can even see on people's fingers wether they are sensitive or not and I think he's right. You can really see it on the fingers. I wonder if other people can spot this subconsciously without knowing it.