I turned 30 this year, and I decided that I'd make it a year of changes. One of those changes was abandoning my sedentery lifestyle and taking up running.

After running my first 5K race, I was hooked. I decided that it would be an interesting challenge to run a half marathon-- and I was right. But I learned a few painful lessons along the way:

Take your training seriously:

In the months between my 5K in May and my half marathon in September, I didn't really change my running routine. I continued running 3-5K a few mornings a week, with a handful of longer runs, no longer than 10K apiece.

I paid dearly for this lack of training during the half marathon, when I realized just how far a 21K race is!

Don't overdo it with water

Race morning: I was excited, I had my bright new technical shirt, my fuel belt, and all the bells and whistles that I thought I'd need. I didn't know what to do with myself in the hour before the race, so I found myself downing energy gels and drinking cup after cup of water.

This was a huge mistake. After running only 3K, I had to stop and find a port-o-let, because my bladder was ready to burst. This ultimately cost me about 6 minutes of wasted time!

Don't try out new gear on race day

I had never used gels before my first half marathon, but I ate them like they were going out of style on race day. The result: I felt bloated and had heartburn as I crossed the finish line.

Save the experimentation for your training! Learn what works and what doesn't before race day!

Keep a positive attitude

The first 3K of the race were great. I was pumped, I was happy, and I felt optimistic. But after my ill-timed bathroom break, I got into a mental funk. Instead of keeping a positive attitude and thinking of how great it would be to cross the finish line, I beat myself up for wasting time and ran the rest of the race like it was a chore.

You're doing this because you love it! Remember that on race day!

Leave time to recover the next day

My half marathon was on a Sunday, and I was back to work the very next day. That's to say, I hobbled and dragged myself there. I was unbelievably stiff and sore after the race. Do yourself a favor and leave time to recover the day after!

Come 2011, I'm setting more realistic goals for my races. Having a successful run is all about common sense and pushing your limits-- but knowing those limits well enough not to have a disappointing result.