The Apple Watch can now monitor and measure your fitness. It may also send you an alert every few months, letting you know if your fitness is not good. If the notifications bother you and you want to turn them off, read the following article.
How to turn off notifications the easy way
While setting Low Cardio Fitness alerts in the Health app, disabling is not done from there.
Instead, to turn off notifications, open the "Watch" app on your iPhone and go to "Heart". Change "Cardio Fitness Notifications".
How To Stop Apple Watch Cardio Fitness Alerts The Hard Way
While disabling Low Cardio Fitness alerts is one way to stop seeing them, there is a better way: improve your heart function. Higher levels of fitness have been linked to lower risk of heart disease, stroke, type 2 diabetes, high blood pressure, dementia, Alzheimer's disease and some cancers. Just look at this list by the American Heart Association.
It is also important to remember that your physical condition is measured against other people age and your gender. If you are 60 years old, your fitness level will of course be lower than you were in your 20s. Apple does not expect everyone to be at the same level of fitness.
Increasing your cardio fitness requires time and exercise. If you are just starting out, try increasing the number of steps you take per day. After a few weeks, you will be able to see your heart rate go up Health application.
To check your heart rate, open the "Health" app, tap "Browse", tap "Heart," and then tap "Cardio Fitness."
Source of information: howtogeek.com