Thanks for mentioning gardening, that's definitely a workout. Especially on my back slope when I have to hold weird yoga-ish positions for a long time.
Beyond that I walk a fair amount (maybe 5 -10 miles/week total, nothing purposeful just getting here and there, I try not to use the car for short distances and there are a lot of things within a short distance), I bounce on the exercise ball I use as a desk chair (seriously, that helps), I do crunches on the exercise ball every now and then, regular housework, swimming in the pool (actually I usually play basketball when I'm in the pool, not a big swimmer) (there's an in-pool hoop), and get to the gym occasionally. Way too occasionally since my workout buddy moved away last year. (Schniff, still miss her.)
I'm getting my first bike in like 20 years! I'm super-excited. I already walk a lot, I want to start riding for the more in-between trips (not super-short, not long). Grocery store, that sort of thing. Getting a basket and a rack. This is it, ain't she a beauty??