I'm earned a BSE in Engineering Physics and a MS in Biomedical Engineering from U of Michigan. Been in the workforce now for about 6 years. I am now applying to medical school at age 30.
1) I've always wanted to be a doctor, it was something that was felt natural to me. Out of all the jobs I've ever had I have always enjoyed the human relationship aspects of them. I simply feel really good about myself when I'm able to help someone. For instance, there are some people who look at disabled people and wonder "it must not be a good life they live, it's got to be hard." Instead I think "I wonder what I could do to help them, help them overcome their disability."
I actually applied to medical school in 1998 but didn't get in. So now I'm applying again after working for 6 years. I actually feel more comfortable about this now than when I was younger. I now have a wife and a son. It puts a completely different perspective on my life and what I should do with it.
2) Been a software engineer and manager for 6 years. Worked at 4 different jobs. Worked at a tech consultancy and 2 startup jobs. When I first started in this field I was working between 50 - 60 hours a week, often on the weekends. I've curtailed that down to 40 hours a week. I don't want to work any more hours than that.
3) because I applied when I was younger, I had all my pre-reqs in. I did take the MCAT again last August and got a 31S. I was quite happy with that...I wasn't supposed to do better than 85% of the people who take the test but I did. I studied really hard for that exam. I started in late March and averaged 15-20 hours a week. That is hard to do on top of having a job and wife/child. So I think I'm up to the academic challenge med school will present. I have my LORs from the first time I applied, and I'm going to ask my graduate mentor for one, and a few of my bosses (CEO's actually!)
4) Yes I'm happier. I find software engineering generally dull and unchallenging. There are challenges, on a daily basis, but they often do not translate it making the company materially stronger. That's my problem with technology. I work my butt off and have no real say in how well the company does. I can build (and have built) several great products and yet our companies still didn't do well. It's just unfulfilling. Now when I volunteer at the ER on a regular basis, I often (however not always) feel better about myself when I leave.
I've been incredibly blessed in this world. I have great parents and siblings, an even more wonderful wife, and now a son who is just the best living thing on this earth. I live in the middle of San Francisco, I make great money, am healthy, and have wonderful friends. I've been blessed 10 times over. But I didn't get here all by myself. I had help along the way from other caring people who wanted me to see success and be happy.
Because of this, I want to give back to people and help them be blessed like I have. And I've found the way that I can do that. There are many ways I could channel my desire to do something for the greater good (teacher, social worker, fireman) and I want to be a doctor. I become probably the most important person (outside their immediate family and close friends) in a patients life and look at all the good you can do for them! It's really amazing and I have such respect and admiration for good doctors who really treat the patient and not the disease.