Probably hard to believe, but you can improve your daily walk. Studies show 
that being around forests, woods, mountains, rivers and oceans is very healthy for humans. These areas have more highly charged ions, which in turn improves your energy and mood. In fact, the Japanese call waking through the woods, “forest bathing”.
The other improvement is to walk (or at least part of your distance) in an inline 
fashion, placing one foot in front of the other and twisting each shoulder 30 degrees so it rotates toward you midline. This requires twisting the spine, which according to Dr. Carl Jelstrup, DC strengthens the gluteus muscles and leg muscles, improving balance and helping to maintain proper pelvic and lumbar function.
Another way to change things up is to try interval training while you walk. Walk as fast as you can for 60 seconds; then slow your pace and walk for 90 seconds. Then repeat 15 more times.