if you've never tried it, find a legit boxing gym and show up when it's open.  tell the owner you want lessons.  if you see people taking selfies or recording their workout you're at the wrong gym lol.  best workout and shape I've ever obtained has been through boxing. 

 I haven't tried it and I don't doubt it. How often do you go 

 at least once, sometimes twice per week.  feels great when I get 2 workouts done in a week. 

 I should have mentioned a coach I had when I was living in another place was a Cuban boxer and taught that style.