The letter to your parents about your dream can be considered as a informal letter
What are the points that should be included in the letter?
Informal letters are private messages sent to friends and relatives to let them know how your life is going and to show your regards. Typically, an informal letter is addressed to a friend, member of the family, or intimate acquaintance.
The highest regard is bestowed upon the medical profession. My life's ambition is to become a doctor in order to assist those who cannot afford to receive pricey medical care. Become a doctor and help a lot of individuals and their families. Saving lives brings happiness and inner peace that surpass all other feelings.