Maintain a clean and healthy home as an example for others to follow is the correct answer.
As they say every good thing or initiative starts from yourself. If you want the country to be clean and pollution free then first of all you have to stop polluting.
Obviously then the others will watch you and learn a good ting or two and follow you or get inspired by you and then stop polluting.
Both Kyla and Tia will be in their zone. Even if they dicrease their heart rates by 20 beats per minute from 175 beats per minute. 155 beats per minute still falls under kyla's target heart rate zone and Tia's target heart rate zone.