Elly Lee discusses her experience climbing stairs to improve her cardiovascular endurance. She found the activity challenging at first but feels she is improving. On her first attempt, she had to stop and rest while climbing but was able to go further on her second try. Going forward, she plans to push herself more without stopping and use a buddy for feedback to help her improve. Climbing stairs helps build cardiovascular and muscular endurance by taxing the heart, lungs, and muscles until exhaustion.