I agree. Many people never reach their full potential because of fear or having unrealistic expectations. This could be as simple as not understanding how much time and effort is required to achieve a goal, which could cause them to be discouraged before even getting there.
I always try to assess situations as best as I can with the knowledge and resources provided to me, and then I just go for it. I put 110% in it and I give myself time to achieve my goal. Persistence and not giving up can go a long way :)