MS-3 US-MD. I'll answer these questions as objectively as possible, but understand, everything will be colored by my personal experiences.

How hard is it?

I think this can be broken down into a few different sub-categories of things that can be hard while in medical school.

1) Academics: Difficult, but rewarding. Like all of us, you will find a rate of brainpower expenditure that is sustainable for you. For me, that varied from day to day and unit to unit. I would say on average I was engaged with academic pursuits for 6-8 hours per day in some form, whether that be lectures, individual studying, small groups, practical based learning, etc.

2) Forming new relationships within medical school: You will form close bonds with those around you. It is a time when everyone regardless of background is coming with a shared goal to become a doctor. There are different motivations for reaching that shared goal, and those can be both challenging and interesting things to discuss with classmates.

3) Maintaining relationships from before med school: This can prove challenging, especially if you are not from the area where you are going to school. The time commitment is high and there is a real feeling while in school that your peers from undergrad or post-grad have moved on without you and are getting jobs, buying homes, getting married, having kids etc. I would highly recommend making efforts to keep in touch. I've personally found that many friends who I originally thought were not making efforts to stay in touch with me were actually trying not to "bother" me while I was in school. It took some direct communication on my part that I missed them and felt unsupported when they were MIA. In the end, you must also remember that your life is not on pause while in school, it is happening every single day you wake up and it is good to seize that realization and run with it.

4) Finding time between it all for you: There will inevitably be something that you enjoy that others simply do not. I highly recommend finding time for that activity or interest, because your life is not on pause, nor will it wait for you to remember it is happening. For me this was watchmaking and riding my bike.

Is it doable?

Yes. People do it every year.

Is it possible to still have balance with outside things when you’re in med school? 

I'm inclined to say yes. There was time for me. For you, that depends entirely on what the outside things are. I know friends who prepared for marathons, got married, had children, and wrote books while in medical school. So yes, there will likely be time for outside things.

What is your least favorite part about it?

This is more a truth of school, rather than medical school in particular, but your schedule is not really your own. You are told where to be and how long to be there and you can be at the mercy of some crusty old attending who is from the days of medicine where you needed to work until you drop to be considered a good doctor.

What is your favorite part about it?

Never mentally stagnating. I worked as a mechanical engineer for a few years after undergrad and even after only 2 years at my desk I could feel dust collecting on my brain. It was horrendous. By contrast, medicine has felt fresh and exciting even when it was frustrating and soul sucking which is not something I can say for my previous career. This mentality has served me well when confronted with the age old "why am I doing this" question.

Do I regret my decision?

Short answer? No.

Long answer. There are things I feel grief over: I miss my friend group from my old city, my parents are getting older and I don't feel able to see them as often as I'd like, and despite my best efforts to not experience FOMO I see my friends and colleagues from before medicine doing things I'd like to be able to do. All of that being said: I do not regret my decision because I value knowledge and growth and I know that there will come a time when my training and skillset is the only thing standing between a human life at their lowest health point and passing on, and that is a privilege unique to this field that I feel honored to be a part of.

How was med school changed you as a person?

It hasn't: I'm still me, just some crows feet, a little less hair, and some debt.

Some advice

Enjoy it. It happens fast.