I started this two years ago as part of my preparation for a hiking trip with Ben Stafford. I started using the stairs instead of the elevator or escalator when it was possible. I stuck with it and I have been taking the stairs two steps at a time for the past two years. I have stronger leg muscles and I climb stairs faster than people who take them one step at a time.
Are you out of breath after you climb the stairs? If you start taking the stairs more often and taking them two steps at a time, I bet within 6 months you will no longer have that problem.
Start this weekend. Small changes like this in your everyday life can make a difference. They have for me.