I know that it's entirely possible to lose your love for a subject - I'm very lucky that I'm maintained the same passion: for technical aviation, since I was about 19, but I have a great many friends who have switched out of the subjects we studied alongside each other.
I'm a (relatively) crusty old bu66er now, but let me offer my own example. I decided at 19, halfway through the first year of my BEng, that my passion was for aviation.
I scraped together enough money for flying lessons whilst I was a student, went solo a few months after I graduated, got my PPL (and my first job in a technical aviation role) about 18 months after graduating.
I didn't have holidays, drove a clapped out old car, rarely ate out - and saved all my money for the flying lesson I could afford once a fortnight. But I got there.
And, my salary as a 22 year old graduate trainee in the Ministry of Defence was, allowing for inflation, almost certainly a lot less than you'll be making as a junior physician. Yes, okay, you'll have student debts, but nonetheless a great many people have managed to scrape enough together to learn, and then fly - I happen to be one of them. If we all could, you can. Fly gliders or microlights if it's cheaper and scratches the itch, but learn about flying, and learn about yourself in that environment.
Later I upgraded to a CPL (and just to mention it, a PhD in aeronautical engineering), whilst holding down a full time job, for much of that time, less well paid than I'd have made had I gone into medicine instead of aeronautical engineering.
Now having been rude and moralised at you; your profile says you're in Milton Keynes. If you want to see what being a pilot is like, drop me a PM - I own 1/20th of a perfectly serviceable aeroplane sat at Cranfield, pretty much representative of what you'd do the bulk of your private and professional licence training in - if you don't mind chipping in a few quid towards the fuel, you're very welcome to a bit of air experience sat next to me.
G