When grocery shopping avoid the carts. Carry two reusable shopping bags instead. You buy less and work more. And don't shop while hungry.
After rolling out of bed, start the day with fifty to one hundred jumping jacks. Gets the blood moving and kick starts the metabolism.
Don't eat anything within four hours of when you go to bed.
Eat a piece of bread with olive oil forty-five minutes before meal time. It will dull your appetite so you eat less and still feel full.
I guess it's not really a "habit" in the sense of walking more or taking the stairs... but, for a while now, I have been doing a stretching routine, and 40 each of push-ups and sit-ups every morning.
Really helps me "limber up" and get a good start on the day.
Stretching is good. Flexibility lowers the odds of injury.