What i want to do in the future. is it a good idea?

im thinking of becoming a doctor or a nurse and saving money for a while then joining doctors of the world and go around the world to help people in different countries then when i retire i want to join the american red cross so i can help people some more and then when im not working with the red cross a want to be a volunteer fireman to help more people. is this a good idea> if its not give me some tips please on what to change or on anything.