pipe and knife.

seriously, just been working the heavy bag on my own for a long time. Hit pretty hard but no true training other than shaddow and mirror, emulating what I see on tape and in books. Whenever I see something new I do it over and over in slow motion to develop coordination until it feels natural. (Example, my left hook was shit for a long time. Very weak. Then I slowed it down to almost nothing, rep after rep, concentrating on form, now it feels as natural as my right.) Then I pick up the pace little by little and then I've developed natural power. Good technique first, power follows naturally.

That's why I asked the question "if you had to pick one..." Would love to take something formally but can't decide what. So many great disciplines to choose from...