I also live in Houston. Years ago I belonged to a health club and did the stair climber with a plastic book holder, so I could get some technical reading done while working out. For the past seven years, I have been exercising outside almost every day, alternating between running and bicycling. With a long history of foot problems, I finally found a pedorthist that made some super orthotics. I have a strict rule to never run two days in a row (that's where the bicycle comes in), and I've been essentially injury free ever since. I listen to tons of tech and entrepreneurial podcasts with behind the neck open ear headphones (e.g. Nike Flite) for safety, so it is not "wasted" time, and almost all of my exercise is on a bike path. In Houston summers, I am up at 7am to be outside before the temperature hits 80 degrees. Above that temperature, I find myself too drained by exercise to be alert for the rest of the day.
"10,000 Point De-lurk" is the earlier post. I will be posting about my infrastructure-related ideas and the "Railroad-baron money" concept in the near future.