Some good replies here.
With regard to degrees etc. The first introduction is the course application form, in my opinion higher grades, and more of them, will always shine out - with those in turn backed up by experience.
One of my youngsters has wanted to be a vet since forever. Piles of soft toys with colds and bandages (makes for interesting reading on the application form!) for as long as I can remember.
By age 9 had already had years of various experience - from lambing, through to large/small animal illnesses, to plucking chickens for the freezer (along with the many questions of what was coming out when the bird was prepared for table).
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NB: 7 years of hard work to qualify, longer than qualifying to be a doctor.