I just got back from my walk. I walk in a cemetery which is also a sculpture park. It is quiet, beautiful, and usually not that populated with live people.
As I walk, I incorporate some of my strength-training exercises into my 3-mile circuit. The environment takes the strength-training ritual to another level. It feels good to stretch outside and pause to notice my surroundings. Usually a hawk that lives there flies by, and in the warmer months, I'm likely to see a Blue Heron by the water.
So next time you take a walk, go to a park or other interesting place and use a little creativity when it comes to objects needed for step-ups, lunges, push-ups, squats, bench dips, calf raises, and so on. Pay quiet attention to how your body feels. Be happy that you can do those 20 lunges.