Half marathon

So Ben and I are both doing a half marathon this May. We started our training program this week. I really like the program cause it mixes up your workouts and you get Fridays off. Monday was just a strength and stretching day, but yesterday was a 3 mile run. Now, I've been running at the gym about 4 days a week and typically run about 3 miles at a time. So, I figured this run wouldn't be too difficult. Here's where I made the mistake. My brother said he was going to run outside, so I decided to do the same. I mean, yeah it is cold (like 38 degrees), but the sun was out so I thought it wouldn't be too bad. I have a 3 mile course mapped out and so I put on my MP3 player and headed out. I forgot how much your lungs burn when running in that cold weather. YIKES! Much different than the 70 degree climate-controlled gym. So, I finished my run and was exhausted. It is much harder to run outside than on a treadmill indoors. Today's workout is either a 2 mile run or cross-train (biking, swimming, walking, etc). I'll wait till the end of the day to decide which option I'll choose.