Preparing to go 140.6 miles in under 17 hours gives one many things to worry about. Can I swim 2.4 miles in open water? What if the waves are too high? What if the current's going the wrong way? Will my goggles work? Will I have a flat tire? How high are those hills? Will there be a headwind? How in the world am I going to run a marathon after biking 112 miles? Will I look good while doing it?
So many worries, and so many miles and hours to dwell on them. Paying attention to the details, big and small, is one of the keys to getting through the day. But stressing over details you can't control wastes mental energy, at best, and can sabotage your swim, bike, and run if you let the wrong details take control.
What not to worry about
On the swim. No Ironman takes place in an indoor swimming pool, so there are probably going to be waves. You're going to swim right through those waves, and you'll find they're much less of a problem than you thought. Remember: you float. At Providence 70.3 in 2009, the swim was in a semi-protected bay, but with the trailing end of an overnight thunderstorm still overhead at start time, the waves were around 18 inches. Consider that the pro's still came out of the water in about 21 minutes, and my own swim time is still my fastest 70.3 swim at 41:22.
On the bike. Popular theory is that somewhere around 1492 this guy from Spain proved once and for all that the Earth is not flat. More recently, this other guy from Spain proved that mountains are no obstacle, especially in France. Oh yeah, you're going to find some climbs, even (relatively speaking) at Ironman Florida. They aren't going anywhere, and they are not getting any smaller, so take 'em as they come, get to the top, and keep on going. Nearly every climb has a corresponding descent, so get ready to enjoy that free speed on the way back down. And that headwind thing? Somewhere along the 112 mile course, you're gonna find it. It can be incredibly frustrating cranking along into a good headwind, but what can you do? Keep on cranking, stay in your zone, and remember that every headwind can also become a tailwind at some point.
On the run. Whether you're running a stand-alone marathon or tacking it on at the end of Ironman, it's still 26.2 miles. It's no farther after going 112 on the bike than when you run a marathon by itself. One foot in front of the other. One mile at a time.
What to worry about
Equipment. Check and double check and triple check every piece of equipment in the weeks and days and hours before the race. Make sure all your clothing fits perfectly, is adjusted right, and works like you need it to when you're actually using it. Don't just pull on your wetsuit in the bedroom - take it to your pool or open water swim area and make sure you can get it on & off, the zipper works, no tears, etc. Take your ride to your local bike shop for a good look-over at a minimum. As Chris McCormmack can attest (2008), the worst kind of DNF comes when you're having a great day, everything's gelling, and then a derailleur cable snaps and your day is over.
On the other hand, remember Chrissie Wellington's flat in Kona, in 2008? She kept her head, stayed calm, got back on the bike, and won!
Nutrition/Hydration. Practiced, and hopefully perfected during training, sticking with your nutrition plan can be the make-it or break-it element over which you have the most control. Knowing what you learned about your needs during long rides and runs, take in exactly what you know you need. Take in less, and you may end up slowing down from lack of fuel rather than mere fatigue, or in the med tent. Take in more, and you risk bloating and a really uncomfortable rest of the day.
Attitude. Even if everything goes perfectly on race day, there really is only one thing that will get you to the end: your unwavering commitment that you will keep going until you cross the finish line. If you give in to the voice that keeps whispering, "I can't do this," you're going to fight it all the way, and it just might win. You'll probably hear that voice plenty through the day, and every time you'll remind it about all your training, all your planning, how much you want this, and that you are NOT going to stop until you hear Mike Reilly's booming voice, proclaiming to the world, "You Are An Ironman!"