How do I train in One Inch Punch ?

[taoistscholar]

focus on internal martial art. Try chi gong

[selfdefense@opt]

Did you win?
If you are still into this have a look at the Punch/Block Power Charger at http://www.bushipower.com/pbpc.php it serves the function of the kunso and tetwan (the Chinese terms).
Makiwara training is essential also. A genuine wood makiwara post with a bit of flex is preferable.

[Dragonfire671]

My advice would be ........... Start train with a heavy bag and start from a distance, then continue. Then get closer and closer. I was taught that your power doesn't come from your arm but from your legs and hip. the motion and coordination must be perfect. You could seriuosly hurt yourself.

[selfdefense@opt]

One inch punch training

Heavy bag is good and totally agree that the power comes from the earth through the body and out the point of impact. But there is no mysticism here. It is just the matter of aligning the parts of the body so that force is tranmitted directly between the point of impact and the earth.
People get hurt by having a misalignment of the body parts. To prevent this the stabilizer muscles must be developed to deal with misalignments. I'm experienced with the makiwara. When I get tired I start to mess up on the punches. The stabilizer muscles prevent injury.
This is where training with the chi'ishi and nigiri game comes in. They develop the stabilizers, as well as the major muscles, and thereby reduce the risk of injury.

[oni kaizoku]

First off, I have to agree with the stupidity of your bet...you should never become macho enough to make a stupid bet that you can't back up...

As per your question- I had a really cool boyfriend that allowed me to practice the one-inch-punch on him...and I suggest finding someone who is willing to let you train on them, because it's a totally different experience to hit a person than it is to hit a heavy bag.
From my experience, the force is in the body for the most part and in the mind, not the arm. You have to send the force of your hips and body through your arm and into the person you're hitting(kinetic energy).
It only took me a few days to get it right...to the point where I could knock my boyfriend back and send him sprawling on the far side of the room...and he was considerably larger than I am...by about 9 inches in height and about 95 pounds. Of course, I had to stop when his abdomen started to get really sore...but he was a good sport about it. He would even let me spin my 'chucks around him as he stood belly to belly with me, praying that I wouldn't accidentally crack him with the 'chucks...which I never did...is that a cool, trusting boyfriend or what?
Anyway, none of this will help you if you don't already know how to punch someone effectively...in which case, you're screwed no matter what...