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What really matters is how badly you want to achieve this dream. At 35 with 8 years of education, you will only be 43 when you can start practicing medicine. That gives you at least 20 years of a medical career, which is certainly worth your time. The only disadvantage I can think of would be the financial burden if you need to borrow a great deal of money to pay for your schooling. That means you will need to work longer and retire later if you have a large student loan.
My suggestion is to go for it!