Although it was supposed to be 3 regrets, I'm going with 5:
1 - I should have studied more English when I was a kid, I didn’t realize at that time how important this would be for me, and I skipped many private school classes I had. Fortunately I caught up in time, but still I’d be speaking much better had I studied more when I was a kid;
2 – Although I have a decent GPA (among the best 17% of class), still with more efforts in my final 2 years (I have a down GPA trend as I focused on my internships) I could possibly be among the Top 10%;
3 – I should have done some Extra Curricular/Social Works when I moved abroad this would have not only given me a better profile but also made me a better person, nevertheless I don’t regret that I took advantage to travel around Europe, and I can say that I’ve been to more places and known more cultures than I could possibly imagine 5 years ago;
4 – I shouldn’t have stopped working out when I moved to Europe, now I have 3 months to get in shape, it’s going to be harder to go with you guys to the Everest

;
5 – I wish I had the guts to apply earlier, with 29-30 years, many schools get more picky with the profile.
Having said all that, especially the last part I don’t regret too much, because I wouldn’t lived many things in did in my life, and perhaps I wouldn’t met the amazingly incredible people I’ve been meeting here.