Know where the stairs are located for safety first and then make them a part of your regular activity. Taking an elevator can mean standing and waiting. I've walked half a flight of stairs. My heart is pounding. The first time up the stairs will be the hardest.
Fitness improves with time.
Park the car on the opposite side of the parking lot. There is little competition for that space. The Replace the car with walking and riding a bike. There are times when walking isn't practical. However, there is nothing keeping me from just taking a 10 minute walk before starting a session.