Sometimes the greatest obstacles to achieving a dream can be the self. We become critical of the self, or even stop believing in the self. A dream does not have to be grand, it could be something small or even daily goals - of course dreams can also be grand as well. The self - doubt does not always breed at the implicit level to begin with. Sometimes is can take root from the external forces, against the barriers that continuously push us down. These are particularly prevalent in educational systems, where we face invisible systemic barriers - particularly those who are of a minority, or even a (dis) ability.
Yes there will be barriers, where there is sorrow, self doubt that shifts from external to internal. These doubts should never sway or stop you from believing in yourself. Ultimately you are in control of your destiny. What you see in the mirror is a reflection of you - Show yourself that you are beautiful even through the struggles. There will always be someone or something that will act as a barrier, never allow these to stop you from dreaming.
When we dream we are living, we become alive. It is our human nature to do so, because we tend to think ahead, and foresee. To allow yourself back into the position of dreaming and doing, remind yourself of the why. Once again begin - begin even if it is a baby step, begin to in-still the hope within.