I used to "efficiently" take one trip upstairs when taking any items up, but now I make it a point to take one trip for each set of items (so I go up and down the steps more per day).
I park farther away in parking lots to walk more and hopefully less chances of door dings on my car!
I walk the groceries in, one bag at a time, instead of trying to stack them all on my arms to make one trip like I used to do (although that does give you a good workout - ha!)
I'll walk around while things are heating up in the microwave or simmering on the stove.
Just not sure where I could add in more than I already have. . .