The beauty of boxing (martial arts as a whole, really) is the countless metaphors it offers.

You learn discipline: fat and out of shape will increase the probability that you get your ass handed to you. Same goes with life - party it up too hard, start indulging in drugs, start prioritizing women over self, allow yourself to rest on a plateau, and you will soon find yourself on the floor seeing stars.

You learn that taking hits is inevitable. Are you going to cry and tap out as soon as the wind is knocked out of you? Again, in life, maybe you get fired from your "perfect job". Maybe your unicorn cheats on you. Maybe a great friend backstabs you. Maybe your business fails. Maybe you have to work not one but two dead-end jobs to make ends meet. Maybe your boss calls you a worthless employee, the laziest, biggest piece of shit he's ever had work under his watch. Taking hits teaches you how to endure. Reflection (on losses) is a means to sharpen your game, not sink into a pool of tears in search of pity.

As Cus D'amato taught, you learn that fighting is overwhelmingly psychological. Cus had Mike Tyson visualize himself as the undisputed champion of the world each night before going to sleep. This practice quite literally scrubbed out any doubt lingering in his mind to the point that he knocked out weakness before literally knocking out his opponents. Mental fitness is paramount. If you do not have a Cus D'amato to walk you through these steps, you can always look to great people scattered throughout History as a compass. Imagine them by your side coaching you. Internalize mindsets which emphasize strength. Do this repeatedly until they become a part of you.

Offense - Mayweather notwithstanding, you must strike your opponent to walk away victorious. Applied to life at large, this means you must go after what you want with impunity. Don't be afraid to ask your employer for a promotion. See a girl on the street you dig? Chat her up. Want to learn a musical instrumental? Practice-practice-practice. If you do this many times over in one area of your life, odds are that it will affect other areas of your life.