There have been times in my life where people have either overestimated or underestimated what I can or cannot do. The thing that needs to be remembered and even more importantly shared among everyone, is that no one else should decide what your limits and strengths are.
Seeing strengths in yourself is a little different. Sometimes you need someone to kick you in the butt and say: "Hey you got this!"
But if people pressure you or push you to do something that you believe you cannot do or just in general, don't want to do, then that is wrong. Sometimes it is for our benefit, but some people cannot stand to see others rise; waiting for the fall.
Then there is the situation where you are trying something new or attempting something outside of your comfort zone. Maybe you just need to do it. Whether it is a situation of choice or necessity, you are still telling yourself that you can do it.
There will be people that will question every twist and turn. People will not believe in you. The most important thing is that you believe in yourself.
Just remember that every idea in science was once believed to be crazy and impossible!
Nothing is impossible! One of my favorite quotes states this very fact: "Nothing is impossible, the word itself says I'm possible!"
YOU are possible. Every chance you take is one worth trying even if you fail. Don't let others hold you back, because the only one to blame would be yourself. They aren't the ones stopping you. You are the one holding yourself back.
Something people need to learn is to let go of valuing others' opinions because a lot of people don't actually do things in your best interest.
So believe in yourself. Do what you have to. And when anyone dares say "you won't be able to," say "I'll show you!"