I'll give my two cents as well...
I'm a third year resident.
My life is really quite demanding. I work anywhere from 60 to 80 hours per week. I generally will have four 24-hour periods per month away from the hospital (oftentimes a weekend day, but sometimes a weekday). I generally have to say at the hospital late every fourth evening (and sometimes overnight). My wife is saddled with many of the household responsibilities, as I really just don't have time to pick up the cleaning, change the oil, do the laundry, cook, etc.
I come home from work quite tired, most days. I do my banking online so I can pay bills from the hospital during some downtime. My email goes unchecked for days. Calls don't get returned for days. I let my family/friends know that if they need to talk to me that day, they need to state this in their message. I am less involved, even over the phone, with my brothers, my sister and her children, and my parents, than I ever have been.
Holidays and birthdays aren't always celebrated on the correct day. Christmas last year was celebrated the 24th. My birthday was celebrated three days later. I spent Valentine's day and night at the hospital. I spent Christmas day and evening and the 26th morning at the hospital.
Training is very difficult. The stakes are higher than they ever have been in one's work life, almost regardless of prior work experience. What other job demands you to save a life of a patient on the other side of the hospital, whose name you don't even know, at 3am? The training for medicine is all encompassing for a reason; the stakes are high.
There are incredible highs and lows. There was a code that I ran (note that generally as senior residents, we are the highest-levels on the floor of the hospital, without physicians who have completed their training) that lasted a LONG time (almost 20 minutes), I was just about to pronounce the patient dead, and the patient regained a pulse. Although I thought we had done a disservice to the patient initially, four days later I visited the patient and she was talking, and coherent (no anoxic brain injury). Perhaps if I weren't there, the patient wouldn't have been intubated (nobody else there was able to), and perhaps the outcome would have been different.
When there is a bad outcome, you take this home as well. We surround ourselves with illness, death, and this can really wreak havoc with one's psyche.
I write all this to encourage those of you who are pre-med. I absolutely would do this again, because in general I really love my job. I cannot imagine another job which would allow me to use my head, to use my hands (to do various procedures), and to use my demeanor (I absolutely believe that a good physician needs to be able to interact with patients in a very unique, open manner; with humor, with warmth, with respect). When the day isn't going so well, I can switch gears; I can focus my energies on teaching the medical students various physical exam skills, I can teach the interns about a disease a patient on service has, or I can take a LONG lunch.
Many people go into the field for the wrong reasons, and those people know who they are when they are interns (because they dread waking up in the morning!) That is why I would never blankly encourage someone to do this; it is SO all-encompassing. You lose friends, hobbies, etc... and even though I felt I was relatively informed when I was a premed in knowing what choice I was making, I don't think it's possible to fully appreciate the level of sacrifice until you're actually making it.
But if you have the interest, the dedication, and most of all the humanity, then this could be a great ride. Patients let you into their most private, darkest hour, and have faith that you can help. And even when your medicine fails, your humanity shouldn't.
Good luck to all of you!
IT'S THE FREAKIN' HOLIDAY! I WANNA RELAX, DRINK, EAT, AND BE MERRY TOO JUST LIKE EVERY OTHER NORMAL PERSON! 
