Having a well planned and well rehearsed pacing strategy in any race can mean the difference between success and failure, especially if you are on the race course for the better part of a day.

A few weeks ago, I completed the Oliver Half Ironman. I somewhat overdid things on the bike and paid the toll on the run leg.

Through months and months of training, I have become very in tune with my body. I know, almost to the beat, where my thresholds are, and when I am exceeding my level of conditioning. I know exactly when I am "under-doing" and "over-doing" things.

During my training, I practiced my cycling and running pacing strategies and knew exactly what I had to do. I knew at exactly what heart rate I needed to work at to achieve my 3 hour bike split, and I knew that this would not do to much harm to my body ahead of the run.

I started the bike leg at my rehearsed pace and felt really good, never feeling like I was exceeding my training and fitness. As I progressed through the course I let my discipline and attention to my race plan slide, just a little at first, and as the finish line approached, I picked things up.

I ended up riding a 2:45 bike split, my heart rate was, on average, about 8 beats above the upper limit I had set for myself in training.

All that attention to pacing strategy during cycling practice had gone out the window. And boy did I ever feel it in the middle of the half marathon.

The first 5km of the run also saw a slide in my self discipline. I allowed the adrenaline of finishing the bike leg and the energy and excitement of the crowds to push me through the first 4km at a completely unrealistic half marathon pace.

The price: a 1:55 half marathon, filled with pain and suffering. The middle 7km was spent running from aid station to aid station.

Mind vs. Body (Fightticker.com)

I felt like a UFC referee in the middle of a battle between two heavy weights -- except the fighters were my body and my mind. Body wanted to walk or stop, but my mind was saying "No way! Go hard!"

I ended up only walking through aid stations while I took on fluids and nutrition, and crossed the finish line at 5 hours and 15 minutes, 15 minutes faster than my previous best time. I rank my time a 10 out of 10, but my pace execution gets a big fat 0 out of 10!

If my time was so great, why am I sweating my pacing strategy so much? For me, a Half Iron allowed me to see the strengths and weakness in my training. I now feel very confident that I have physical conditioning to push through a full Iron. However, it's clear that I need to develop better psychological control in order the execute my pace strategy and meet my race goals.

The Oliver Half was forgiving enough and I was in good enough shape to blow my pacing and still come out on top. However, a full Iron will not be so forgiving. One error in judgment could cost me my race, not just a decent finish time. A solid pacing strategy is both comfort and contingency: the comfort to know you're on track and the contingency when something goes sideways.

Over the final few weeks before the big day, I will be investing time to improve my psychological powers of patience and concentration, so I do not have another day like I had in Oliver. It's no wonder that tri coaches like Troy Jacobson and others have training resources dedicated to mental toughness. Ironman is as much a mental test as it is a physical test.

Trust me when I say I will be practicing to perform! And so should you.

James Greenwood is a competitive tri and multisport athlete currently training for Ironman Canada 2009. A level 1 Triathlon Coach, he holds a post graduate degree in Exercise Science, and is a Certified Strength and Conditioning Specialist through the NSCA. James is also currently the resident health and fitness programs expert at MyPypeline.com, and has starred in a number of multisport specific fitness videos.