For those of you who have too busy a lifestyle to workout, I have good news: exercise is cumulative.
Simply put: a little bit of exercise throughout the course of the day will count as a workout.
Maybe leave a couple of dumbbells at your desk so when you take a break you can do arm curls (3 sets with each arm). (A heavy book also will fit the bill.)
Later in the day, go to the stairwell and do alternating step-ups (3 sets, 3 minutes each).
If you stop at the store for lunch or on the way home, take the farthest parking space from the building, which will add some walk time.
By following the tips above, we just added 20-25 minutes of exercise into your day.
Be creative, have fun and start enjoying a healthier lifestyle.