John Kavanagh is perhaps the most well known for being Conor McGregor’s coach. The irishman, now 43 years old, is founder and head coach of Irish MMA gym SBG Ireland and the current president of the Irish MMA Association.

Kavanagh undertook MMA after watching UFC in 1993. He competed in some of the earliest local MMA in Ireland and UK and is the first Irish man to get a black belt in BJJ.

Recently espn caught up with Kavanagh and a number of respected coaches to get their perspective on the Biggest Mistakes they’ve made. Here’s how Kavanagh described his:

Maybe not a very good one, but I regret my first 10 years or so of MMA and grappling with people a lot heavier than me. I’m now left with a pretty serious neck condition that means my own ability to grapple is severely hampered. One wrong move could have me off the mats, in pretty severe pain for months. This has already happened a few times. I take comfort that I’m still able to demo and coach and use lessons learned on next generation, but I miss the mat.

This technique is designed to rupture the major collateral ligaments in the elbow joint. It is powerful enough to cause an avulsion fracture. Luckily for FM he does not have to worry about this next Saturday. Or does he?

A post shared by Coach Kavanagh (@coach_kavanagh) on Aug 19, 2017 at 1:38pm PDT

Kavanagh was previously quoted saying:

“When I started off I was working security five nights a week and construction at the weekends, just so I could train Monday to Friday and pay the rent and try and keep this idea going.

“But for someone who shows and has a decent background and is young enough that they are going to get somewhere with it, the only thing I’m interested to see is are they enjoying it.

“Because whatever it is you want to do, I don’t take care it what is, it’s going to take you ten years of doing it daily before you get anywhere.

“No matter what you want to get to an expert level at, you have to put in the time.

Among others the same article also consulted Tristar head Firas Zahabi about his worst mistake:

I would say, though, that sometimes I have over and underestimated opponents. It’s very difficult to estimate how hard someone will be to take to the ground. You see who has taken them down in the past and who hasn’t, try to predict off their track record, but MMA math is not always perfect. A lot of times it comes down to styles and decision-making and things you can’t equate before the fight. I try not to predict too much how good someone will be in any particular area.