I'll spare you guys from the details, but in short I became a doctor because my parents wanted me to but I realized that my true passion is in aviation. I'm 31 years, just finished residency, and want to become an airline pilot! (don't want to live with this big of a regret, realized that I can't do that). Any advice on to how I should go about? how up can I really go if I start from no flight experience (i.e captain at a major? FO at a major?) at my age?
Thanks!
Well, you sir are in luck, (sorry, this is assumptive), you have just joined the best resource in the world to help guide you. Soooo, welcome to JC, we're characters to say the least, we argue about everything from politics and current events to the vast reaches of the industry on this site. good and bad, but I'll be damned if
@Derg didn't build the best networking website for pilots on the web.
Soooooo, first, don't ever buy a Beechcraft Bonanza, you'll thank me later.

seriously
Here's the good,
you joined JC
you have a great career already that you can fall back on.
you probably won't need to borrow money for training
the airlines are hiring like gangbusters, ( the regional airlines that is ) some at the majors, ya know, where the big bucks are /myth
there are great jobs in aviation outside of the airlines ( unless you're gung ho on the airlines )
The bad,
you will probably spend 60k - 80k for training ( well you did go to med school so...)
once you have your ratings, you will probably make 25k - 45k for
at least 5 - 6 years ( 2 instructing, 2 - 4 at a regional/charter/cargo)
If you instruct part time plan on it being 6 - 8 years
Pros:
chicks dig pilots, at least until they see your pay stub
we wear uniforms, uhh oh wait, this belongs with the cons
you get to fly airplanes, meh whatever that is j/k
Cons:
you won't make much money
you won't make much money
you won't make much money
you won't make much money, until you get on with a major (which really you're probably thinking about what's known as a Legacy Airline)
welp, there ya go. Seriously, welcome to JC, ask us questions during your training, I'm a Flight Instructor, so hit me up or any of the others on here. I have a feeling you're going to be at least a private pilot soon. You caught the aviation bug, it shows. welp, that's all the Jameson has to say right now
Good luck Doc