I have been walking almost every day here in Austin for years, both for general exercise and because it makes my back have fewer aches and pains. I can choose to walk just about any time of day or night, but have settled into the early morning as my preferred option.
Besides the practical concerns of walking in a hot climate at the coolest time of day, getting out when nobody else is around, and enjoying clean air before the morning traffic creates a smog cloud, there are aesthetic reasons for walking very early. The routes I take are not the popular paths favored by joggers and bikers. I wouldn't go near the Town Lake Hike & Bike Trail, or the Barton Creek Greenbelt at any time of day. Instead I prefer areas around apartments, shopping centers, and the few undeveloped places near our home.
Because of the early hour, I often meet animals that I otherwise would never see. Even in our built up area of Austin, there are opossums, owls, turkeys, gray foxes, skunks, coyotes, and deer. These creatures are usually quite surprised to see a person during what they consider to be "their" time. Birds tend to sing as if they are actually greeting the new day. I've noticed that the mockingbirds have a different sort of song that they use very early. If I pass the same way a bit later in the morning, they are not nearly so flamboyant.
The skies alone are reason enough to get out early. The clouds, moonsets and sunrises are an ever changing work of art. While I used to enjoy the morning skies when I was driving to work, nothing beats being able to look at them without having to pay attention to the rush hour traffic as well.
Little surprises spice up the experience too. This past winter, I went out the morning after we had a hard freeze. The temperature was still not above freezing, and I was treated to the most spectacular display of frostweed ice sculptures that I've ever seen. Other times, when it has been raining a lot, there are myriad creeks and rushing streams in a normally dry terrain. These sparkling miniature floods only last a short time before all the water drains away and things return to their usual state. The sun's first rays on dew-covered spider webs and grass produce millions of tiny rainbows that look like jewels. The smell of wet juniper, blossoming trees, or warming tall grass is most intense during the still of the morning.
Whether it is a beach hike, a cypress swamp trek, a mountain expedition, or just a stroll around our neighborhood, I cannot think of a better way to exercise than to get out for a morning walk.