The Right Path?

How do you know when something is right for you? When someone tells you it is impossible you automatically want to prove them wrong. But what if what they say you can't do isn't what you really want to do. So if you don't do it they are right, but if you do it you aren't happy. So my predicament is that I am unsure if this career path is right for me. But if I don't follow through people will say I gave up. I don't think I'll ever be completely sure of what I want to do for the rest of my life. But I do know that I want to do it for me. I don't want to map out my future because of someone else's snide comments. No one's future should be decided by someone else. Follow the path marked out for you. It may take some time to find it but it will be worth it.