Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great.
If your company of friends and those around you are small people, then it is likely you are small and will remain small. Your growth will always be limited by the size of their little thinking, lack of ambitions, self-belief and confidence. And very likely, they are people with many complaints and negative things to say. On the other hand, the successful people, the greats, will influence your thinking positively and value-add into your life, and encourage you to become great like them. Small people who have never gotten near success and greatness will tell you that it is impossible to get there. Great people who have worked their way there will tell you that getting there is at all possible. Therefore, surround yourself with great people around you so that greatness can be birthed in you.