I've been doing a ton of walking lately (trying to get in my 10,000 steps each day) and have been feeling some tightness in parts of my legs as a result. My hamstrings, calves and Achilles tendons could all use a bit of stretching out, and yoga is great for that, especially downward dog and warrior poses. While things aren't perfect, the stretches certainly help to improve my condition, and there's no need to restrict stretching to one or two days a week. They can be done daily, just like taking multiple vitamins.
As I've been taking my daily brisk walks, I remind myself to take deep breaths at stoplights, relax my neck and shoulders, let my arms hang, and turn off my mind (except to be mindful of traffic). The side effects of carrying principles of yoga into everyday life have been good. My body gets less tense, stays relaxed for longer periods of time, and my walking gait is quick, yet unencumbered by excess moving parts. It's a nice benefit.