If there is something that you want to do, that you feel strongly about, go ahead and give it a go. Come what may, the road ahead is only going to get interesting. If anyone is being negative about it, that is their right. Do not let them get to you. If you can somehow find something good and beneficial in that, more power to you. But if you do not, let it slide and keep walking. You do not have to engage and create unnecessary tension in your being. Unless of course, it interferes with your work then you better set the record straight. However, if the negativity comes from within you, telling you that you are not qualified and playing all those mind games with you, you say thank you to them and you keep walking. Remember, do not unnecessarily waste your precious limited energy on things that do not affect the work that you are doing. Give yourself a chance. Do it right and do it well.