Earl Nightingale said, "Never give up on a dream just because of the time it will take to accomplish it. The time will pass anyway .” He was right, but some dreams need modifying.
My daughter wanted to be an actress, she was very talented but after graduating from college and going to several talent calls, in New York, she was wise enough to move to her second parallel love teaching dance while still acting in a local community theater.
Here are my suggestions:
When you have a dream think, of all the work alternatives that could be just as satisfying if you accomplish it. What is the driving force behind that dream that is motivating you? If you want to be a doctor, think of the reasons you want to be a doctor, is it to treat illness or something else?
Are there other professions that would give you the same amount of satisfaction?
Look up resources online that list occupations. There are many free tools like List Of Jobs - List Of Jobs - informationvine.com. It has lists of jobs by types: Business, Health, Finance, Entertainment, Travel, Computers, Real Estate.
Talk to people in the parallel professions and see how satisfied they are with their work.
Try to gain an internship in the parallel profession to test the waters.
Finally, see if any of the experiences you will gather from your work can loop back to your original dream.
I have seen people use their additional work experience to allow them get the jobs they desired.
"Destiny is no matter of chance. It is a matter of choice. It is not a thing to be waited for, it is a thing to be achieved."
Work on your destiny every day and do not give up.