There never seems to be enough time during the day to get in the proper amount of training. Especially if you're the the type of person who works 40+ hours a week and has other obligations on top of that, albeit school, family, etc. You need to ask yourself the question, "how important is my lunch time to me?" Now, not all of us have a gym within 5 minutes of work, or a shower room at work, but for those who do, this question should be answered simply. There's no reason to not give up your lunch hour a couple times a week to get in some solid training. After all, if we don't break up the day, and sit on our rears for 8+ hours, we could end up like this:
I'll admit, getting up at 4am sucks. No matter how dedicated you are, it's hard! The toll it takes on your body continually mounts. After all, 12 hours later, you're still at work. And getting to bed at a reasonable hour most nights is tough enough.
This is where I like having the option to get in some training over my lunch break. It's never that long, but I always make sure it's a quality effort.
For me, I generally hit the pool. My office doesn't have a shower, so going out on a run straight from work isn't an option. Although, I wish it were. We have a nice path around a few large ponds right across the street and some friendly neighborhoods. But, in less than five minutes, I'm at the gym and changing into my swim gear. Generally, I give myself 35 minutes of pool time. When I'm pushing it, I can get my 2km swim completed in that time. I know, the 70.3 distance is 1.2 miles, but going about 1,931m doesn't seem like a
nice even number to end on. Other days, I'll throw in some high intensity work, but go for less total distance. Say an easy 500m warm up, then 10x100m at threshold. The total distance I'm putting in is never substantial, but the quality always needs to be there.
The same goes for running. From time to time, I'll go to the gym and hop on the treadmill. I know I won't have the time to get in a basebuilding effort, but 30 minutes is more than enough to get in some great intervals or a solid tempo run. Be sure to spend a good 5 minutes warming up, though, at an easy pace. You have been sitting at your desk or in meetings the bulk of the morning I'm sure. So best be sure you're legs have some blood flowing and you shake out the cobwebs.
One of the biggest benefits I get from training over my lunch break, is that my afternoons are awesome! Getting out of the building and putting some strain on my aerobic system gives me a huge second wind to finish out the day. I always feel I have more energy and am much more alert and alive. It's like adding a double shot to a cappuccino, without the dehydration, headaches or crash. And you get the thought of knowing you put in quality time training, while the rest of your co-workers stuffed their faces with food, most likely having gone out to a local restaurant or fast food joint.
The only downfall for me, is having to eat my lunch at my desk while working. It's not a big deal, but you don't quite enjoy lunch as much. However, the pro's heavily outweight the con's in this situation. It's also nice to have bosses who support your athletic endeavors. So look for those if you can!