From then, Jeffries won 7 National titles, a European Gold medal and ticked of a sweet 106 fights as a boxer. Now, he spends most of his time managing his two LA Boxing gyms, and running a Youtube channel that aims to educate people on "how to get better at boxing."
In one such video from a few months ago, Jeffries offers up his advice on how to throw a punch with the absolute maximum power.
To help viewers get the most our of their punch - so to speak - he explains how trained fighters do exactly that, and the moves you can incorporate in your next bout with a bag.
"You might think the most powerful punch is the overhand right," he says. "It's hard, and you can do some damage with that, but it's not the hardest one-puncher you can do." He goes on to explain that a straight right hander actually has the potential to be the most powerful punch you can throw—provided your technique is correct.
"Punching power starts in the feet," he says, "as long as you're doing the right technique with the footwork. It'll increase the power of that straight right hand, probably twice as much."
While you generally move forward with your front foot in boxing, followed by your back foot, Jeffries says, in this case, you step your back foot forward first, followed by the front foot.
"The reason why it's so hard is because I'm not just turning my hips and getting body weight behind the punch, I'm also getting the force of my body weight movement forward behind the punch as well. With that force, plus the weight transfer, plus the full extension of the arm, exhaling, staying relaxed... that right there is how you punch as hard as you can."
Watch it below: