Hi Mary - great question which has many answers which usually start with "it depends...". With the world today you will find you can commence in one profession and easily move into another one which as times change. Changes in Business and Government's approach to issues like Climate Change, can open up new career opportunities for you. As Al suggests, try and find something you are really passionate about and go for it - invest time in training and education with the approach of "to be the best at whatever you possibly can be".
Many years ago a great friend of mine taught me the below which has turned out to be very true:
18 years old = you know everything
21 years old = you know you know everything
25 years old = you begin to doubt
30 years old = you begin to learn !
Good Luck in your endeavors !