Dreaded Stairwell

Last summer Lee and I did P90X, it was indeed extreme and my body was firmer than it has been since high school. Once the 90 ended (90 days) we stopped and my body went back to being a bowl full of jelly. Crap. A few months ago I decided I would take the stairs as much as possible at work or when I was out and about. Most mornings I walk into the building at work and I think "I will just take the elevator today, my arm is tired" or "I didn't sleep enough last night so I will take the elevator". After laughing at myself briefly I waddle my way to the stairwell to climb the 4 flights of stairs it takes to get me to my office. I know it doesn't seem like much, but at 7:00AM it seems like a lot to me. Why am I so lazy? How does one get motivated to work out? Everytime I want to work out I get home and the craziness of having young children sets in and I lose ALL willingness to do so. Couple that with hating to shower more than once a day and there are my two huge excuses. If someone could show me the light to get me past that I would greatly appreciate it.