The moral of the story, there is always time to get in some type of fitness. That fitness could be going to the gym, it could be taking your dog for a walk. Many times when I come into work early (which early is around 10-12) I sometimes see a group of guys jogging on the Red River trails. They meet up in downtown and then run a few miles during their lunch break. (Side note: very rarely is it ok for someone to run with their shirt off. If you have to question whether or not you should, you just answered your question!)
Things to do on your lunch break:
Head to the gym for an abbreviated or extended workout
Walk or run up and down the stairs at your office
Take a walk around the neighborhood/block/etc where your place of business is located
Stretch at your desk
Run the Red River trails
Arm wrestle the person in the cubicle next to you
Bring a football to work and go throw outside
Do pushups and sit ups at your desk
If you rode your bike to work, ride it around the neighborhood/block/etc where your place of business is located
Go play disk golf at the Clyde Fant park
These are just a few examples of things that you can do in 30 minutes a day to become a bit healthier. If you have suggestions or comments, feel free to send me a few and I will post them. Remember, fall is coming and fall=fitness!!!
Before starting any exercise, diet or health routine, first consult your physician to make sure that your body is healthy enough for physical activity.