12/11/2013 07:05 pm ET Updated Feb 10, 2014

A New Kind of Fight

When you think of a fight, what comes to mind?

Punches thrown? Brutal bruising to the face and body? In the end, a victory for one and defeat for another?

As boxers, we learn that to win the battle, we must get to know our opponent. What are their tendencies? Will they wear down as the battle goes on?

Done with an open mind, familiarity can counter their hostility and the battle is won.

But what if the battle was with yourself, not fighting your image or self-worth but an internal disease? What if your opponent was inside of you?

My story started late 2011, when my physical at the doctor's office was to have a regular checkup to see my full body function.

I was in for a surprise. I was in the best shape of my life, running four miles, three times a week, and then two hours in the gym. My physical at the doctor's office was a formality. I remember thinking, "Don't waste your time, Doc."

I felt healthy, I had slim to zero body fat. I was supposed to get a clean bill of health and pursue my dreams as a professional boxer.

Then the first punch was thrown: Pow! What could have possibly be wrong? My doctor called me back with test results and told me I had kidney failure. I didn't believe her at first. Had this person not seen me? I was ripped. Form the outside, how could anything be wrong?

A few days later, a biopsy was required. Confirmed. "Marc Coronel, you are diagnosed with FSGS (focal segmental glomerulosclerosis)." Kidney failure!

Believe it or not, I actually struggled with this decision, but I knew what I had to give up was my passion for boxing.

But that's when my fight begins.

It was harder then any punch I had ever taken, and just 27 percent of my kidney function was working. The doctor placed me on 60 milligrams of prednisone (steroid), 20 milligrams of Lisinopril (high blood pressure), 150 milligrams of Bupropion (anti-depressant), 20 milligrams of Omeprazole (acid reducer), to name a few.

The side effects were symptoms of aggression, agitation, anxiety, mental depression, mood changing, shortness of breath and a mass amount of weight gain, due to increased appetite.
My life went from protein shakes to five to 10 medications in 24 hours. Even though the disease may prevent me from boxing, what it has done has also reoriented and reinvigorated my mental outlook.

My 12-round fight has just started. Without being able to box physically, my mental preparation comes everyday when I wake up. I ask myself, "You only fail If you fail to try." "What do I do now?"

Training, running, lifting, being in the gym is all I knew and what I loved. Growing up boxing pretty much saved me. It disciplined me, gave me an outlet for my aggression. I was scared of what my life would look like without it.

So what did I do? The answer came back to me. Keep training not as a boxer but a trainer, a coach, a person who knows how to fight!

The solution to overcoming the side effects was to help others, both in and outside of the ring. I thought, you have got to work hard to get better. You think my kidneys are gonna go easy on me? No way. I train people to push past their limits, to work hard, and sweat. That's how I trained as a boxer. That's how I fight my kidney disease.

You want to feel what a true reward is? Work harder then you've ever worked, physically push yourself beyond what you thought you were capable of, and come out the other end a new person. Don't take life for granted. Never give up, and always fight for your dreams. Regardless of what kind of punches life may throws at you, you counter that move.

I was a boxer. Now I'm a fighter. I fight every day, I fight for my kidney brothers and sisters. I fight to be healthy, I fight to be positive. I fight kidney disease.

A link to my video for kidney disease is here.